Week 7 · Chapter

Chapter 7 — Social Stratification & Class

Introduction to Sociology Free sample edition

The module's primary reading · ~35–45 minutes · Objective 5 (analyze social stratification, class, and global inequality — caste and class systems, income versus wealth, poverty measures, social mobility, the Davis-Moore thesis against the conflict view, and modernization against dependency and world-systems perspectives — reading income, poverty, and cross-national inequality data with their sources and years), building on Objective 1 (apply the sociological imagination — connecting personal troubles to public issues — and the three major theoretical perspectives (structural functionalism, conflict theory, symbolic interactionism) to interpret a social phenomenon, naming the level of analysis each works at and placing the discipline's founders with the ideas and works they are known for) and Objective 2 (describe and evaluate the major sociological research methods (surveys, experiments, field research and ethnography, secondary-data analysis), distinguish reliability from validity and a population from a sample, and read a social statistic critically — what it measures, over what population and period, what it shows and does not, and whether it is a correlation or a cause) · Read it first this week; the lecture, the slide deck, the tutorial, the quiz, and the Sociology in Action Workshop all build on it.

In plain language

Every society ranks its people, and the ranking shapes who gets a good school, a safe street, and a second chance. This week names that ranking social stratification (the sorting of people into layers by money, education, and power). You will learn to tell income (the money that comes in, like a paycheck) from wealth (what a household owns minus what it owes, like a bank balance). You will see how the government draws a poverty line, how people move up or down the layers, and why sociologists still argue about whether the layers are fair. Then you will read the real 2024 income and poverty figures one careful step at a time.

Why you already care about this

In its report Income in the United States: 2024, the Census Bureau put the median household income at 83,730 dollars. Its companion report counted 35.9 million people in poverty under the official measure. That is 10.6% of the people the measure covers.

Those numbers can feel far away, but you meet the layers they describe every day. Two classmates work the same shift at the same coffee counter and earn the same pay. One goes home to a paid-off house; the other sends part of every check to a student loan. A friend takes an unpaid summer internship that you could not afford to take. A neighborhood gets a new grocery store, and rents on your block start to climb.

None of these moments feels like sociology. Each one is a moment when a layer becomes visible. This chapter gives you the words for those layers and the habits to read the numbers behind them without being fooled.

By the end of this chapter you will be able to:

define social stratification and sort a case into slavery, caste, estate, or class, and into a closed or open system;
tell income from wealth in a household's finances, and find the median and the mean of a small set of incomes;
tell absolute poverty from relative poverty, and explain why the official measure and the Supplemental Poverty Measure give two numbers;
compare Marx's two classes with Weber's class, status, and party, and name a person's life chances;
classify a move as intergenerational, intragenerational, or structural mobility;
lay out the Davis–Moore thesis, Tumin's critique, and the conflict view without declaring a winner;
read the 2024 median household income and the official poverty rate four ways, with the arithmetic shown.

Carry this line with you: a paycheck is a flow, not a fortune — read the balance too.

Where we are

Already covered: Week 1 gave you the three perspectives and Marx's bourgeoisie and proletariat. Week 2 taught the four data questions and the percentage point. Weeks 3 and 4 showed how culture and the self are learned. Week 5 showed how groups and organizations hold people, and Week 6 asked who gets to decide what counts as breaking the rules.
This week: how a society ranks its people into layers, the difference between income and wealth, how poverty is measured, how people move between layers, and the competing explanations for why the layers exist.
How they connect: Week 6's conflict account asked who has the power to define deviance; this week asks who has the money, the prestige, and the power in the first place, and reads the answer with Week 2's four questions.
Where we're going next: Week 8, Midterm Review & Exam, pulls Weeks 1 to 7 together and adds the level-of-analysis habit, and Week 9 then carries this week's ideas from one country to the whole world.

Week 2 is the chapter this one leans on most. There you learned to ask four questions of any figure: what is measured, over whom and when, what it shows and does not, and whether it is a correlation or a cause. Section 7 runs the Census Bureau's 2024 figures through all four. Week 2 also gave you the percentage point, the unit for the difference between two percentages, which you will need when two poverty measures disagree. Week 1's macro level, the scale of whole societies, matters all week: stratification is a macro pattern, even though you feel it in micro moments like a paycheck or a rent notice.

1. See the layers: stratification and its systems

Walk through an illustrative city from one end to the other. Near the river, houses have gates and three-car garages. A few miles inland, apartment buildings share one laundry room per floor. Past the highway, families rent rooms in houses that once held one family. The people in each area did not each decide, one by one, to live in layers. The layers were there before they arrived.

That is the first idea of the week. Inequality is not only a set of individual differences, like who is taller or who studied harder. It is a pattern built into the whole society.

Social stratification is a society's ranking of its members into layers by wealth, income, education, family background, and power, a pattern built into the whole society rather than a list of individual differences.

Societies have built their layers in different ways. Sociologists name four systems.

Slavery is a system of stratification in which some people are owned by others as property and have no say over their own labor or standing.
A caste system is a closed system of stratification in which a person's standing is fixed at birth and does not change through effort or achievement.
An estate system is a system of stratification in which standing rests on inherited rank tied to land and law, with only narrow room to move between ranks.
A class system is an open system of stratification in which achievement as well as birth shapes a person's standing, so movement between layers is possible.

Two more words describe how much movement a system allows.

A closed system is a system of stratification that allows little or no movement between layers, because birth fixes where a person belongs.
An open system is a system of stratification that allows movement between layers, because what a person achieves can change where they stand.

Worked example — sorting four illustrative societies. Read each description and name the system.

Society one. A child's family line decides the work the child may do, whom they may marry, and where they may live, and no amount of effort changes it. Standing is fixed at birth: a caste system, and closed.
Society two. Some people are bought and sold, and the law treats them as property. That is slavery, the most closed system of all.
Society three. A small group inherits titles and land; the law grants them rights others lack. A few commoners can rise by serving the titled families, but only so far. An estate system, mostly closed.
Society four. Children of factory workers sometimes become engineers, and some children of engineers end up in lower-paid work. Birth still matters, but achievement can change standing. A class system, open.

In words: ask "does birth fix the layer, or can achievement move a person?" Fixed means closed; movable means open.

An open system raises a hopeful question. What if rank rested only on effort and talent?

A meritocracy is a hypothetical system in which a person's rank would rest entirely on individual effort and ability, with no advantage passed on by birth.

Notice the word hypothetical. No society fully runs this way, because every class system still passes some advantage from parents to children. That is why the conflict tradition, which Week 1 traced to Marx, reads the belief in meritocracy in a second way.

A legitimating ideology is a set of beliefs that makes an unequal arrangement look fair and natural, such as the belief that everyone at the top earned it and everyone at the bottom chose it.

Misconception check — "meritocracy is how it works." Students often describe the United States as a meritocracy, as if that word described how the system actually runs. It is tempting, because effort plainly matters in many lives. But meritocracy is a hypothetical ideal, a yardstick, and in the conflict tradition the belief that we already live in one is read as a legitimating ideology. The cure: say "a meritocracy would reward only effort and ability," then ask what else, such as family wealth, also shapes rank.

Memory hook: closed means birth decides; open means achievement can move you.

2. Tell a paycheck from a balance: income and wealth

Picture two illustrative coworkers, each earning 60,000 dollars a year at the same warehouse. On paper they look identical. Now open their bank statements.

Coworker A has 15,000 dollars in savings and owes 22,000 dollars on a student loan.
Coworker B lives in a paid-off house worth 250,000 dollars, left by a grandparent, has 30,000 dollars in savings, and owes 10,000 dollars on a car loan.

Same paycheck. Very different lives. One can survive a layoff for a year; the other is one emergency away from new debt. Sociology separates these two kinds of money.

Income is a flow of money that comes in over a period of time, such as wages, salaries, and returns on investments.
Wealth is a stock of value measured at one point in time: everything a household owns minus everything it owes.

Worked example — the two coworkers' wealth. Add what each owns, then subtract what each owes.

Coworker A owns: 15,000 dollars in savings.
Coworker A owes: 22,000 dollars.
Coworker A's wealth: 15,000 − 22,000 = −7,000 dollars. Negative wealth means owing more than you own.
Coworker B owns: 250,000 + 30,000 = 280,000 dollars.
Coworker B owes: 10,000 dollars.
Coworker B's wealth: 280,000 − 10,000 = 270,000 dollars.

In words: the two coworkers have the same income, a flow of 60,000 dollars a year, and wealth that differs by 270,000 − (−7,000) = 277,000 dollars.

Why is wealth more unequal than income? Wealth builds up. Savings earn returns, a house can rise in value, and a family can pass all of it to the next generation. A paycheck stops when the job stops; a stock of wealth can keep growing across lifetimes. That is why wealth is more concentrated than income.

Honesty note: this course pins no figure for how much of the nation's wealth the richest households hold. A wealth share changes every quarter and is easy to misquote, so it is read at its source, the Federal Reserve's Distributional Financial Accounts, or it is not asserted. The Readings & Resources page links to it.

Income figures bring one more choice: which "middle" to report. Picture an illustrative street of five households with these yearly incomes: 28,000, 41,000, 52,000, 66,000, and 413,000 dollars.

The median is the middle value when every case is lined up from lowest to highest, so half the cases fall below it and half above it.
The mean is the total of all values divided by the number of cases, a figure that a few very large values can pull far above the middle case.

Worked example — the illustrative street. Find both middles.

Line them up. 28,000, 41,000, 52,000, 66,000, 413,000. They are already in order.
The median. Five cases, so the third is the middle: 52,000 dollars.
The total. 28,000 + 41,000 + 52,000 + 66,000 + 413,000 = 600,000 dollars.
The mean. 600,000 ÷ 5 = 120,000 dollars.

In words: four of the five households earn less than the mean of 120,000 dollars, because one very high income pulled it up. The median of 52,000 dollars still sits with the middle household. That is why income is reported as a median.

In practice (your tools). In any free spreadsheet, type the five incomes into cells A1 through A5. In A6, type =MEDIAN(A1:A5) to get 52000, and in A7 type =AVERAGE(A1:A5) to get 120000. Change the 413,000 to 4,130,000 and watch: the mean jumps, and the median does not move.

Misconception check — income and wealth as one thing. Students often use "income" and "wealth" as if they meant the same thing, saying a high earner is "wealthy." It is tempting, because both are money. But income is a flow over a period and wealth is a stock at one moment. The cure: ask "is this coming in, or is this owned minus owed?" The two coworkers share an income and differ by 277,000 dollars in wealth.

Misconception check — the mean as the middle. Students also read an "average income" as the typical household's income. A handful of very high incomes pulls the mean up and leaves the median where it is. When a source reports a median, call it "median household income," never "average income."

Memory hook: a paycheck is a flow; a balance is a stock.

3. Draw the poverty line: absolute and relative poverty

Think about two illustrative people. One lives where clean water is a long walk away and some days bring no meal at all. The other lives in a city apartment with running water and a full refrigerator, but cannot afford a bus pass, a phone plan, or a school trip that every other child in class is taking. Are both poor?

Sociologists answer with two different ideas of poverty.

Absolute poverty is lacking the basic resources, such as food, shelter, and clothing, that a person needs to live.
Relative poverty is having far fewer resources than most people in the same society, even when the basics are covered.

The first person is in absolute poverty. The second is in relative poverty: the basics are there, but the gap from everyone around them shuts them out of ordinary life.

A government that wants to count poverty has to turn an idea into a line. That is Week 2's operationalize step: defining a concept so it can be measured. The Census Bureau has two ways of doing it.

The official poverty measure is the Census Bureau's long-standing poverty measure, which counts a family as poor when its income falls below a threshold set by family size and the ages of its members.
The Supplemental Poverty Measure is the Census Bureau's second poverty measure, which draws the poverty line and counts a family's resources in a different way from the official measure, so it gives a different rate for the same year.

You will also see it called the SPM, the short name for the Supplemental Poverty Measure, the Census Bureau's second way of counting poverty.

Worked example — sorting four illustrative cases. Decide whether each describes absolute or relative poverty.

A family that skips meals at the end of every month because the food runs out. The basics are missing: absolute poverty.
A teenager whose family has food and housing but cannot afford the internet service that every classmate uses for homework. The basics are covered; the gap from others is the problem: relative poverty.
A worker sleeping in a car because no apartment is affordable. Shelter, a basic, is missing: absolute poverty.
A retiree who can pay for food and rent but never for a visit to family or a seat at a community event. Relative poverty.

In words: absolute poverty asks "are the basics there?" and relative poverty asks "how far below everyone else?"

Caveat: a poverty line is a definition, not a fact of nature. Move the line or change what counts as a family's resources, and the count changes even though no family's life has changed. That is why the two Census measures can give two different rates for one year, and why Section 7 reads both.

Misconception check — "the poverty rate is the share of people who are poor, full stop." Students often read a poverty rate as a plain count of who is poor. It is tempting, because the number looks so exact. But a poverty rate is the share of people below a named threshold under a named measure. Change the measure and the share changes. The cure: always say which measure, for which year, from which report.

Memory hook: a poverty line is drawn, not found.

4. Name what a class is: Marx, Weber, and life chances

Picture an illustrative school librarian and an illustrative landlord who owns 12 rental units. The landlord's income is far higher. Yet at a neighborhood meeting, people stand up when the librarian speaks, and the librarian chairs the committee that decides how the new park will be built. Who ranks higher?

Week 1 introduced Marx's answer. In the Manifesto of the Communist Party (1848), written with Friedrich Engels, Marx pictured society splitting into two opposed classes: the bourgeoisie, who own the means of production, such as factories, land, and machines, and the proletariat, who own none and must sell their labor to live. For Marx, class is about one question: do you own the means of production, or do you work for someone who does? By that test, the landlord owns property that earns income, and the librarian sells labor for a salary.

Max Weber, whom you met in Week 1 and again in Week 5's bureaucracy, thought one dimension was not enough. He separated three.

Class, status, and party are Weber's three separate dimensions of inequality: class is economic position, status is social honor or prestige, and party is power gained through organized groups.

A note on words: Week 5 used status for any social position, like student or cousin. Weber's status is narrower. It means the honor or prestige a position carries. When this chapter means Weber's sense, it says "status, in Weber's sense."

Weber also gave a name to what a position does for a person's life.

Life chances are the opportunities, such as good health, schooling, and safety, that a person's position in the layers of society makes more or less likely.

Worked example — the librarian and the landlord, two ways. Read the same two people through each account.

Marx's account. The landlord owns property that produces income: closer to the owning class. The librarian sells labor for a salary: closer to the working class.
Weber's class. The landlord's economic position is higher, with more income and more property.
Weber's status. The librarian holds more social honor in the neighborhood; people defer when the librarian speaks.
Weber's party. The librarian chairs the park committee, an organized group that decides something real, so the librarian holds more power there.
Life chances. The landlord's property makes some things more likely, such as paying for a child's college without a loan. The librarian's networks make other things more likely, such as hearing first about a job opening at the school district.

In words: Marx sees one line, between owners and workers; Weber sees three ladders, and a person can stand high on one and low on another.

Misconception check — Weber's status as Week 5's status. Students often read Weber's "status" as any position a person holds, such as cousin or cashier, because that is what the word meant in Week 5. But in Weber's three dimensions, status means social honor or prestige. The cure: when the word sits beside "class" and "party," read it as prestige.

Misconception check — Marx and Weber swapped. Students also credit the three dimensions to Marx or the two opposed classes to Weber. The cure is a count: Marx's account has two classes; Weber's has three dimensions.

Memory hook: Marx draws one line; Weber builds three ladders.

5. Climb or slide: social mobility

Picture an illustrative family across three generations. A grandmother picked fruit for a living. Her son trained as an electrician. His daughter became an accountant, then lost that job when her firm shut down and spent two years driving for a delivery service before finding accounting work again. Each move is a change in standing, and sociologists sort the moves by what they compare.

Social mobility is movement by people from one layer of a stratification system to another, upward or downward.
Intergenerational mobility is movement between layers measured by comparing a person's position with the position of their parents.
Intragenerational mobility is movement between layers within one person's own lifetime, such as from a first job to a later one.
Structural mobility is movement between layers caused by a change in the economy itself, such as a new industry growing or an old one closing, which moves many people at once.

Worked example — sorting the moves. Name each kind of mobility.

The grandmother's fruit picking to her son's electrician work. A comparison across generations: intergenerational mobility, upward.
The daughter's accounting job to delivery driving. A move inside one person's working life: intragenerational mobility, downward.
The daughter's return to accounting. Still within her own life: intragenerational mobility, upward again.
An illustrative town where the paper mill closes and a regional hospital expands. Hundreds of mill workers lose their jobs while hundreds of new health jobs open. Many people move at once because the economy changed, not because each person changed: structural mobility.

In words: intergenerational compares you with your parents, intragenerational follows you through your own life, and structural is the economy moving many people at once.

Structural mobility is where Week 1's sociological imagination returns. One laid-off mill worker has a personal trouble. Hundreds laid off when the mill closes is a public issue, a structural change no single worker caused.

Misconception check — "every move is personal effort." Students often explain every rise or fall as one person's choices. It is tempting, because each move happens to one person. But when a mill closes or an industry grows, many people move together, and the explanation works at the macro level of the economy. The cure: before explaining a move, ask "did one person change, or did the economy change?"

Pause and choose one of these two prompts.

(a) Describe one move in your own family's history, such as a change of work from one generation to the next, and name which kind of mobility it shows.
(b) Describe one change in a local economy you know, such as a store closing or a new employer opening, and explain how it could move many people at once.

Memory hook: ask who moved: one person, or the whole economy?

6. Explain the ladder: Davis–Moore, Tumin, and the conflict view

Every society you have read about this week has layers. So why do layers exist at all? Sociologists have argued over that question for decades, and the argument is still open.

In 1945, Kingsley Davis and Wilbert Moore published "Some Principles of Stratification." Their answer was functionalist: unequal rewards do a job for society.

The Davis–Moore thesis is Kingsley Davis and Wilbert Moore's 1945 argument that the more functionally important a position is, the more reward it must carry to attract qualified people to fill it.

In 1953, Melvin Tumin answered them in "Some Principles of Stratification: A Critical Analysis."

Tumin's critique is Melvin Tumin's 1953 reply to the Davis–Moore thesis, arguing that functional importance is hard to measure and that stratification blocks talent and passes advantage down the generations.

The conflict view goes further. It reads stratification as the reproduction of advantage: those at the top use their wealth and power to keep their children at the top, whatever their children's talents.

Each account has real strength. Davis and Moore explain why some long, demanding training paths carry high pay. Tumin explains why a talented child born into a poor family may never reach the training at all. The conflict view explains why advantage so often stays in the same families. This course presents all three and declares no winner; you weigh them on evidence.

Worked example — one illustrative unpaid internship, three lenses. An illustrative city agency offers unpaid summer internships that often lead to paid jobs.

Structural functionalism (macro): the internship sorts and trains people for important positions in the agency, so society gets qualified staff for demanding jobs.
Conflict theory (macro): only students whose families can cover a summer without pay can take the internship, so the path to the paid jobs passes advantage down the generations.
Symbolic interactionism (micro): the line "summer intern, city agency" on a résumé signals "serious candidate" to a hiring manager, while a summer spent stocking shelves may be read, unfairly, as "less ambitious."

In words: the first two lenses read the internship at the macro level of the whole society, and the third reads it at the micro level of the meanings people attach in a hiring conversation.

Misconception check — "one theory is right." Students often decide that Davis–Moore is plainly right because doctors earn a lot, or plainly wrong because some low-paid jobs are vital. Both moves skip the weighing. The functionalist and conflict accounts answer different questions, and each has evidence on its side. The cure: state each account at full strength, then name what evidence would favor one over the other in a specific case.

Memory hook: reward the important job — but who decides what is important, and who gets to try?

7. Read the real figures: income and poverty in 2024

Now read the real numbers with Week 2's four questions. The sources are two Census Bureau reports: Income in the United States: 2024 (P60-286) and Poverty in the United States: 2024 (P60-287).

The table below sets out the figures you will work with.

U.S. median household income and poverty rates for 2024, with the 2023 comparisons, from Census Bureau reports P60-286 and P60-287
Figure	Value
Median household income, 2024	83,730 dollars
Median household income, 2023, restated in 2024 dollars	82,690 dollars
Median household income, 2023, as first published in 2023 dollars	80,610 dollars
Official poverty rate, 2024	10.6% (35.9 million people)
Change in the official rate from 2023	down 0.4 percentage points
Supplemental Poverty Measure, 2024	12.9%

One more term helps here.

A dollar year is the year whose prices an amount of money is stated in, so that amounts from different years can be compared fairly only when they are stated in the same year's prices.

Worked example — the 2024 income figures, read four ways. Take the five steps in order.

What is measured? Median household income: the income of the household in the middle when every U.S. household is lined up from lowest to highest income.
Over whom? U.S. households in 2024, from the Census Bureau's Income in the United States: 2024 (P60-286).
What does it show? Work it one step at a time.
- The figure: the median household income was 83,730 dollars in 2024.
- The change: the 2023 estimate restated in 2024 dollars was 82,690 dollars, and 83,730 − 82,690 = 1,040 dollars. The Census Bureau reports the two as not statistically different, so the read is no measurable change, not a rise.
- The dollar year: the 2023 report had published the 2023 median as 80,610 dollars in 2023 dollars, and 82,690 − 80,610 = 2,080 dollars between two statements of the same year's median. That is why a figure always carries its report and its dollar year.
What does it not show? The spread of incomes: a median is the middle household and says nothing about the gap between top and bottom. It is not a wealth figure, and it does not say why households earn what they do.
Correlation or cause? Neither. It is a description of one year's households.

Worked example — the 2024 poverty figures, read four ways. The same five steps apply.

What is measured? The official poverty rate: the share of people whose family income fell below the official threshold, from the Census Bureau's Poverty in the United States: 2024 (P60-287).
Over whom? People in the United States in 2024.
What does it show?
- The figure: the official poverty rate was 10.6% in 2024, which was 35.9 million people, written out as 35,900,000.
- Rate to base: 35.9 ÷ 10.6 × 100 ≈ 339, so the measure covers about 339 million people, or about 339,000,000. The 35.9 million is a count; the 10.6% is a rate.
- The change: the rate was down 0.4 percentage points from 2023, so the rounded figures put the 2023 rate at about 10.6 + 0.4 = 11.0%. A rate rebuilt from rounded figures can miss the published one by a tenth of a point, so read a past year's rate in that year's own report.
- Two measures: the Supplemental Poverty Measure was 12.9%, statistically unchanged. 12.9 − 10.6 = 2.3 percentage points higher than the official rate, and 2.3 ÷ 10.6 × 100 ≈ 21.7 percent higher, because the two measures count different things.
What does it not show? Any wealth figure, the depth of anyone's poverty, or why a family falls below the line.
Correlation or cause? Neither. These are descriptions of one year, not a test of what causes poverty.

In words: about one person in ten was below the official line in 2024, the supplemental measure put the share higher, and neither number says why.

Put the two measures side by side: 12.9% versus 10.6% is a gap of 2.3 percentage points, a supplemental rate about 21.7 percent higher than the official one. A city council reading only one of them would budget for a different number of families than a council reading both. That is the practical stake in naming the measure.

In practice (your tools). You can check every step in a free spreadsheet. Type 35.9 in B1 and 10.6 in B2. In B3, type =B1/B2*100 to get about 338.7, which rounds to the 339 million people the measure covers. Type 12.9 in B4. In B5, type =B4-B2 to get 2.3, the gap in percentage points, and in B6, type =B5/B2*100 to get about 21.7, the percent difference.

Misconception check — "the median rose, so everyone is better off." Students often read a higher median as proof that every household gained. It is tempting, because the median feels like "the typical family." But a median describes one household, the middle one. It can rise while many households lose ground, and here the change was not even statistically different from zero. The cure: say what the median is, then say what it cannot tell you.

Misconception check — percent and percentage point swapped. Students also call the 2.3-point gap "2.3 percent." The gap between 12.9% and 10.6% is 2.3 percentage points, which is about 21.7 percent of the official rate. Write the unit every time.

Memory hook: name the measure, the year, and the report, or the number means nothing.

For more on this week's ideas, the module's Readings & Resources page links to short articles and videos.

Key terms

Social stratification — A society's ranking of its members into layers by wealth, income, education, family background, and power, a pattern built into the whole society rather than a list of individual differences. (first used: 1. See the layers: stratification and its systems)
Slavery — A system of stratification in which some people are owned by others as property and have no say over their own labor or standing. (first used: 1. See the layers: stratification and its systems)
Caste system — A closed system of stratification in which a person's standing is fixed at birth and does not change through effort or achievement. (first used: 1. See the layers: stratification and its systems)
Estate system — A system of stratification in which standing rests on inherited rank tied to land and law, with only narrow room to move between ranks. (first used: 1. See the layers: stratification and its systems)
Class system — An open system of stratification in which achievement as well as birth shapes a person's standing, so movement between layers is possible. (first used: 1. See the layers: stratification and its systems)
Closed system — A system of stratification that allows little or no movement between layers, because birth fixes where a person belongs. (first used: 1. See the layers: stratification and its systems)
Open system — A system of stratification that allows movement between layers, because what a person achieves can change where they stand. (first used: 1. See the layers: stratification and its systems)
Meritocracy — A hypothetical system in which a person's rank would rest entirely on individual effort and ability, with no advantage passed on by birth. (first used: 1. See the layers: stratification and its systems)
Legitimating ideology — A set of beliefs that makes an unequal arrangement look fair and natural, such as the belief that everyone at the top earned it and everyone at the bottom chose it. (first used: 1. See the layers: stratification and its systems)
Income — A flow of money that comes in over a period of time, such as wages, salaries, and returns on investments. (first used: 2. Tell a paycheck from a balance: income and wealth)
Wealth — A stock of value measured at one point in time: everything a household owns minus everything it owes. (first used: 2. Tell a paycheck from a balance: income and wealth)
Median — The middle value when every case is lined up from lowest to highest, so half the cases fall below it and half above it. (first used: 2. Tell a paycheck from a balance: income and wealth)
Mean — The total of all values divided by the number of cases, a figure that a few very large values can pull far above the middle case. (first used: 2. Tell a paycheck from a balance: income and wealth)
Absolute poverty — Lacking the basic resources, such as food, shelter, and clothing, that a person needs to live. (first used: 3. Draw the poverty line: absolute and relative poverty)
Relative poverty — Having far fewer resources than most people in the same society, even when the basics are covered. (first used: 3. Draw the poverty line: absolute and relative poverty)
Official poverty measure — The Census Bureau's long-standing poverty measure, which counts a family as poor when its income falls below a threshold set by family size and the ages of its members. (first used: 3. Draw the poverty line: absolute and relative poverty)
Supplemental Poverty Measure — The Census Bureau's second poverty measure, which draws the poverty line and counts a family's resources in a different way from the official measure, so it gives a different rate for the same year. (first used: 3. Draw the poverty line: absolute and relative poverty)
SPM — The short name for the Supplemental Poverty Measure, the Census Bureau's second way of counting poverty. (first used: 3. Draw the poverty line: absolute and relative poverty)
Class, status, and party — Weber's three separate dimensions of inequality: class is economic position, status is social honor or prestige, and party is power gained through organized groups. (first used: 4. Name what a class is: Marx, Weber, and life chances)
Life chances — The opportunities, such as good health, schooling, and safety, that a person's position in the layers of society makes more or less likely. (first used: 4. Name what a class is: Marx, Weber, and life chances)
Social mobility — Movement by people from one layer of a stratification system to another, upward or downward. (first used: 5. Climb or slide: social mobility)
Intergenerational mobility — Movement between layers measured by comparing a person's position with the position of their parents. (first used: 5. Climb or slide: social mobility)
Intragenerational mobility — Movement between layers within one person's own lifetime, such as from a first job to a later one. (first used: 5. Climb or slide: social mobility)
Structural mobility — Movement between layers caused by a change in the economy itself, such as a new industry growing or an old one closing, which moves many people at once. (first used: 5. Climb or slide: social mobility)
Davis–Moore thesis — Kingsley Davis and Wilbert Moore's 1945 argument that the more functionally important a position is, the more reward it must carry to attract qualified people to fill it. (first used: 6. Explain the ladder: Davis–Moore, Tumin, and the conflict view)
Tumin's critique — Melvin Tumin's 1953 reply to the Davis–Moore thesis, arguing that functional importance is hard to measure and that stratification blocks talent and passes advantage down the generations. (first used: 6. Explain the ladder: Davis–Moore, Tumin, and the conflict view)
Dollar year — The year whose prices an amount of money is stated in, so that amounts from different years can be compared fairly only when they are stated in the same year's prices. (first used: 7. Read the real figures: income and poverty in 2024)

Summary

Stratification is a society-wide ranking into layers, not a list of personal differences.
Caste is closed; class is open; meritocracy is a hypothetical ideal and, in the conflict tradition, a legitimating ideology.
Income is a flow; wealth is a stock, and wealth is more concentrated.
A median is the middle household; a few huge incomes pull the mean up.
Absolute poverty lacks the basics; relative poverty falls far below others.
The official measure and the SPM count different things, so 2024 has two rates: 10.6% and 12.9%.
Marx sees owners and workers; Weber sees class, status, and party.
Mobility can be intergenerational, intragenerational, or structural.
Davis–Moore, Tumin, and the conflict view compete; the course declares no winner.

Check your understanding

Work these before looking at the answers — they are ungraded, and the answers (with reasoning) are at the bottom of the page.

An illustrative block has five households with yearly incomes of 22,000, 39,000, 45,000, 58,000, and 236,000 dollars. Find the median and the mean, and say which one better describes the middle household.
An illustrative nurse earns 4,800 dollars a month, has 6,500 dollars in savings, owns a paid-off car worth 9,000 dollars, and owes 4,000 dollars on a credit card. Which of these figures is income? What is the nurse's wealth?
In an illustrative county, the share of residents below a poverty line falls from 16% to 12% over five years. By how many percentage points did it fall, and by what percent?
Name the kind of mobility in each case: (a) a dishwasher who, over fifteen years, becomes the owner of the restaurant; (b) the child of a seasonal farmworker who becomes a pharmacist; (c) thousands of coal miners in one region who move into other work after the mines close.

Answers (worked reasoning — read after attempting)

The incomes are already in order, so the median is the third value, 45,000 dollars. The total is 22,000 + 39,000 + 45,000 + 58,000 + 236,000 = 400,000 dollars, and the mean is 400,000 ÷ 5 = 80,000 dollars. The median better describes the middle household: four of the five households earn less than the mean, because one very high income pulled it up.
The 4,800 dollars a month is income, a flow over a period. Wealth is what the nurse owns minus what the nurse owes: 6,500 + 9,000 = 15,500 dollars owned, and 15,500 − 4,000 = 11,500 dollars of wealth. The paycheck does not enter the wealth figure.
16 − 12 = 4 percentage points. As a percent change, 4 ÷ 16 × 100 = 25 percent. Both are true at once, and the unit tells the reader which one you mean.
(a) Intragenerational mobility, upward: one person's own working life. (b) Intergenerational mobility, upward: the child's position compared with the parent's. (c) Structural mobility: a change in the region's economy moved many people at once.

Next up in this module: the Readings & Resources page, the lecture tutorial, the practice set, the quiz, the discussion, and the assignment — and next week the midterm review adds the level-of-analysis habit, a reading method for every inequality figure that follows.

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