Summary of Labor Economics: Human Capital and Inequality

## Introduction Wage inequality examines differences in wages earned by workers across occupations, skill levels, education, gender, and other characteristics. This guide explains why wage differences have changed in recent decades, how supply and demand for skills affect wages, and what forces — such as technology and globalization — drive those changes. Practical examples and comparisons help connect theory to real-world outcomes. ## Key Concepts Broken Down ### What is wage inequality? > Wage inequality refers to the unequal distribution of wages among workers in a population, measured using statistics such as wage ratios and the Gini coefficient. ### Common measures of wage differences - Wage ratios (e.g., 90–10, 90–50, 50–10) compare wages at different points of the distribution. For example, the 90–10 ratio compares wages at the 90th percentile to the 10th percentile. - The **Gini coefficient** summarizes inequality on a scale from 0 (perfect equality) to 1 (maximum inequality). ### How to interpret changes - A rising Gini or widening wage ratios means greater dispersion of wages (more inequality). - A falling Gini or narrowing wage ratios means wages are becoming more similar (less inequality). ## Historical Patterns (Last ~30–40 years) - Since the 1970s–1980s, wage inequality in the U.S. has increased moderately, not from extreme low to extreme high values. For example, measured Gini values rose from below 0.4 toward the mid-0.40s across several decades. - Relative wages of college graduates compared with high school graduates have increased substantially. College graduates earn notably more than high school graduates, with the college–high school wage premium growing from around a 50% advantage toward roughly a 100% advantage in some measures over the 1980–2005 period. Did you know that the increase in wage gaps has been larger at the top of the distribution than at the middle, contributing to much of the observed rise in overall inequality? ## Forces Affecting Wage Inequality ### Labor supply changes - Rising educational attainment increases the supply of skilled workers: percent of workers with college and advanced degrees has risen since 1960. The share without a high school degree has fallen dramatically. - Female labor force participation and the supply of highly skilled women have increased substantially since 1960. > Supply change: An increase in the number or share of workers with a given skill or credential. ### Labor demand changes - Skill-biased technological change (SBTC): New technologies have tended to complement skilled workers and substitute for unskilled workers, raising the relative wages of skilled labor. - Globalization: Increased trade and offshoring can reduce demand for unskilled domestic labor while increasing demand for workers who can manage complex tasks or work with advanced technologies. > Demand change: A shift in employers’ willingness to pay for particular skills, often due to technology or trade. ### Institutional and policy factors - Declining union coverage and a falling real minimum wage can reduce bargaining power and compressing effects that previously supported lower-end wages, contributing to wider wage dispersion. - Changes in discrimination laws historically reduced overt barriers, although legal regression would have the opposite effect; recent U.S. trends do not reflect a legal expansion of permissible discrimination as a driver of inequality. ## Practical Examples - Example 1 — Technology and wages: A software firm automates customer service. Entry-level agents (low-skill) are replaced by chatbots, reducing demand for those workers and lowering their wages relative to software engineers (high-skill), whose wages rise. - Example 2 — Education premium: In a local labor market, a college-educated worker moves into a managerial role with $80,000 salary while a high-school-educated worker remains in production earning $40,000; the college worker earns 100% more in th