Cohort Effect: 10 Examples, Definition, Types

Cohort Effect: 10 Examples, Definition, TypesReviewed by Chris Drew (PhD)

This article was peer-reviewed and edited by Chris Drew (PhD). The review process on Helpful Professor involves having a PhD level expert fact check, edit, and contribute to articles. Reviewers ensure all content reflects expert academic consensus and is backed up with reference to academic studies. Dr. Drew has published over 20 academic articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education and holds a PhD in Education from ACU.

cohort effect examples and definition, explained below

The cohort effect refers to a phenomenon where people of the same group (‘cohort’) have shared features that differ from other cohorts.

It can refer to age groups, cohort groups in universities, geographical cohorts, and so on.

For example, people of a certain age group may share societal and historical experiences that influence their behaviors and attitudes throughout their lives, which makes them differ from other age groups.

Case Study: The Gen X Cohort Effect

Those belonging to Generation X (born between 1961-1981) experienced vastly different childhoods than their Baby Boomer counterparts. They were raised during a time of increased divorce rates, working mothers, and latchkey children resulting in them becoming more independent and self-sufficient individuals with strong individualistic tendencies. These features gave them unique cohort characteristics and shaped many of these peoples’ mindsets.

Cohort effects can influence several aspects of a cohort’s shared identity, ranging from educational attainment levels to political inclinations.

However, it’s important to note that the cohort effect can also produce unfair stereotypes and characterize people based upon group identity factors rather than the content of any one individual’s character or abilities.

chrisComprehension Questions: As you read through this article, our editor Chris will pose comprehension and critical thinking questions to help you get the most out of this article. Teachers, if you assign this article for homework, have the students answer these questions at home, then use them as stimuli for in-class discussion.

Definition of Cohort Effect

The cohort effect is a term used in scientific studies that refers to the effects of group membership or belongingness on behavior, attitudes, and outcomes (Holford, 1991).

It is an important concept in social and behavioral sciences that helps to explain how one’s age at certain historical times can influence their personality, knowledge, and behavior.

According to Keyes and colleagues (2010), a cohort effect

“…is conceptualized as a period effect that is differentially experienced through age-specific exposure or susceptibility to that event or cause (i.e., interaction or effect modification)” (p. 1103).

The cohort effect primarily focuses on the influence of environmental factors or experiences on individuals who were part of a particular birth cohort undergoing shared experiences at a certain time & place. However, it can also relate to cohorts in a broader sense, such as when teachers say “The 7th Grade students this year are particularly rowdy!”

But it’s important to note that cohort effects should not be attributed to individual differences in age alone.

As Ahacic and colleagues (2007) believe,

“…cohort effects may be because of historical differences in the social or physical environment during childhood or young adulthood, or to differences in the structure or size of a cohort, e.g., baby boomers differ from previous and later cohorts partly due to their greater numbers” (p. 84).

Just because two adults have a twenty-year age difference does not automatically mean they will exhibit significant variation by comparison. So, external societal changes influencing them must also be represented appropriately.

chrisComprehension Checkpoint: Write your own paraphrased definition of the cohort effect. What key points would you include in your own definition? Keywords you might use include “historical factors” and “group membership”. 

10 Examples of Cohort Effect

  • Attitudes towards diversity: Younger generations exhibit more diverse attitudes regarding gender, race, and ethnicity due to a combination of exposure, education, and cultural shaping of thinking through varied media programming.
  • Political attitudes: The Civil Rights Movement of the 1960s shaped the attitudes and beliefs of those cohorts coming of age about social justice and equity during this time.
  • Education expectations: Millennials coming to adulthood in an era marked by skyrocketing tuition fees value education differently than older generations who could pursue degrees without hefty costs.
  • Fashion trends: Bell-bottom pants were prevalent during the 1970s among Baby Boomers; however, Generation Z prefers high-waisted jeans reflecting current aesthetics popular among young people today.
  • Social media usage: Gen Z now dominates social media, with platforms like Instagram and TikTok playing central roles in how they experience entertainment culture as opposed to Boomers who prefer older platforms like Facebook.
  • Health outcomes: Smoking rates have declined steadily since the 1950s for each successive birth cohort because of changed attitudes about health risks associated with smoking after scientific evidence emerged.
  • Pop culture influence: Hip-hop music began influencing American pop culture in the 1990s, which shaped preferences in fashion styles, dialects, and dance moves among younger populations than in gen-X cohorts.
  • Economic circumstances: The Great Depression (1929-1939) significantly affected how those who lived through it understood finances leading them to save more money even years after economic recovery set in as opposed to later generations who saw incredible economic growth post-war boom years following World War II.
  • Climate change awareness: Cohort effects shift generational awareness about environmental sustainability concerns. Now, younger generations are exhibiting greater environmental sensitivity leading to evolving behaviors like less meat consumption or switching to electric vehicles for transportation.
  • Interest in traveling: Generational cohort variations extending into travel habits experienced differently according to regions visited. So, Gen Z travelers seek to experience unique, off-the-beaten-track locations with a preference for more immersive experiences.
chrisComprehension Checkpoint: Consider your own generation. What historical factors do you think affect the trending values, beliefs, and behaviors of your generational cohort? Consider the influence of technology, family structures, the economy, and geopolitical issues. 

Types of Generational Cohorts

A generational cohort refers to a group of people who share unique characteristics or experiences which differentiate them from other generations.

These characteristics may include demographic factors like age, gender, ethnicity, and more (Day, 2013).

Here are some different cohorts and their defining traits:

  • Silent Generation: Refers to people born between 1928 and 1945 who grew up during the Great Depression and World War II era. They are often labeled reserved as they value respect for authority, have a strong sense of duty, and prioritize family over individual needs.
  • Baby Boomers: Refer to individuals born after WWII ended from 1946 -1964. The Boomers were characterized by a period of economic prosperity and technological innovations that significantly transformed the way life was perceived, leading to social changes that advocated for freedom, the separation between work-life balance, and anti-war sentiments.
  • Generation X: These are comprised of individuals born between 1965-1980. They are often thought cynical, pragmatic, independent thinkers due to features like increasing divorce rates. 
  • Millennials, aka Generation Y (1981-1996): This group associates digital innovation as a hallmark in changing cultural trajectory. For example, mobile sharing economies combined with smartphones’ internet accessibility allow convergence in communications, driving change towards remote work and entrepreneurial ventures.
  • Gen Z, aka Post-Millennials: Born between 1997-2012, this cohort represents teenagers in a contemporary world dominated by social media platforms and technology trends like AI virtual reality within flexible integrated shared economies driving new entrepreneurship models (Lowry, 2022).

Studying Cohort Effects (Longitudinal vs. Cross-Sectional Cohort Studies)

Longitudinal cohort studies and cross-sectional cohort studies are two major study designs of cohort effect that have differences in design, sampling, data collection, and analysis (Yang & Land, 2016).

Let’s have a quick look at the main differences:

1. Study Design

The longitudinal cohort study design follows a group of individuals over a period to gather longitudinal data. 

The cross-sectional study design examines different groups of individuals simultaneously for collecting multiple variables (Yang & Land, 2016).

2. Sampling

Longitudinal cohort studies are based on selecting participants who initially do not have the event under investigation, along with systematic measures over a long period to evaluate how the incidence changes by keeping their baseline records. 

Cross-sectional studies, on the other hand, tend to use sampling techniques stratified by demographic information like age group, sex, ethnicity, and more (Yang & Land, 2016).

3. Data Collection

Longitudinal cohort studies require continuous data collection at different periods to determine how variables change over time within an individual.

On the other hand, cross-sectional cohorts seek to collect data from different groups simultaneously using survey methods such as questionnaires that are collected once (Yang & Land, 2016).

4. Analysis

The major challenge of a longitudinal cohort is missing data due to attrition since participants may drop off from the initial sample leading researchers to inadequate follow-up rates. 

This is less likely in cross-sectional peer-reviewed articles due to the wide variety of subjects in a sample frame (Yang & Land, 2016).

chrisComprehension Checkpoint: Name one major benefit and one limitation of longitudinal cohort studies over cross-sectional cohort studies. Now, consider one benefit and one limitation of cross-sectional cohort studies. 

Importance of Studying Cohort Effects

Understanding cohort effects is crucial as it enables us to recognize how the environment influences people’s perspectives towards various aspects of life, creating effective interventions.

The importance of cohort effect is significant for several reasons:

1. Understanding Public Health

Cohort effects offer valuable insight into how changing societal and lifestyle factors may influence disease outcomes.

They are aiding surveillance and interventions during routine public health planning, eventually identifying crucial variables influencing morbidity and mortality rates in targeted populations.

2. Formulating Social Policies to Bridge Generational Differences

Cohort effects permit comparative demographic analyses on age groups about varying optimal outcomes.

These analyses are based on trends in different generations’ behavior while implementing tailored approaches considering socioeconomic factors.

3. Academic Research

With longitudinal cohort studies giving room for comparisons between different study periods eventually provide more solid evidence for distinguishing causal factors from correlational ones.

Such tasks include determining factors related to cognitive decline with aging.

4. Business Marketing Interactions

Cohort analysis provides real-time tools used by businesses to analyze various demographic trend patterns. They include consumer preferences and spending habits as the individual ages.

Thereby, companies develop products targeting users in specific age groups resulting in strategies for more efficient use and channeling of marketing resources.

5. Improved Policy-Making Procedures at the Local Level

Cohort trends have demonstrated how political elections can generate impacts depending on generations where they categorize voting behavior.

So, Millennials are poised toward center-democrats, whereas Generation X leans toward conservatives posing realities that should be catered to by policymakers.

chrisComprehension Checkpoint: Imagine a cohort study that finds that the Gen Z cohort has found it harder than previous generations to break into the housing market due to the global economic conditions of the 2020s. What public policy initiatives might a government implement in response to this cohort effect? Once you select a policy initiative, consider some possible unintended consequences of the policy initiative you selected.  


The concept of cohort effect is critical in understanding how different variables over time can shape people’s thoughts, behaviors, and values. 

It helps us explain why individuals from distinct demographic groups have differing views regarding cultural perspectives, political beliefs, economic priorities, and health outcomes. 

By exploring the cohorts that represent these groups- ranging from the Silent Generation to Gen Z-we gain crucial insights that inform health policy development and implementation while guiding academic research directions. 

We also understand how historical context shapes generational differences like those during the WWII climax or post-industrialization periods, for instance.

So, cohort effects enable policymakers to create targeted policies and programs tailored to specific population groups.


Ahacic, K., Parker, M. G., & Thorslund, M. (2007). Aging in disguise: age, period and cohort effects in mobility and edentulousness over three decades. European Journal of Ageing4(2), 83–91.

Day, I. N. M. (2013). Molecular genetic epidemiology. Springer Science & Business Media.

Holford, T. R. (1991). Understanding the effects of age, period, and cohort on incidence and mortality rates. Annual Review of Public Health12(1), 425–457.

Keyes, K. M., Utz, R. L., Robinson, W., & Li, G. (2010). What is a cohort effect? Comparison of three statistical methods for modeling cohort effects in obesity prevalence in the United States, 1971–2006. Social Science & Medicine (1982)70(7), 1100–1108.

Lowry, D. (2022). Aging and the life course: Social and cultural contexts. New York: Rowman & Littlefield Publishers.

Yang, Y., & Land, K. C. (2016). Age-period-cohort analysis. New York: CRC Press.

Viktoriya Sus

Viktoriya Sus (MA)

Viktoriya Sus is an academic writer specializing mainly in economics and business from Ukraine. She holds a Master’s degree in International Business from Lviv National University and has more than 6 years of experience writing for different clients. Viktoriya is passionate about researching the latest trends in economics and business. However, she also loves to explore different topics such as psychology, philosophy, and more.

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This article was peer-reviewed and edited by Chris Drew (PhD). The review process on Helpful Professor involves having a PhD level expert fact check, edit, and contribute to articles. Reviewers ensure all content reflects expert academic consensus and is backed up with reference to academic studies. Dr. Drew has published over 20 academic articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education and holds a PhD in Education from ACU.

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