GITNUXREPORT 2025

Effect Sizes Statistics

Effect sizes vary by field, with psychological interventions typically large at 0.80.

Jannik Linder

Co-Founder of Gitnux, specialized in content and tech since 2016.

First published: April 29, 2025

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Effect sizes tend to be smaller in social and behavioral interventions compared to biomedical interventions

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The difference in effect sizes between randomized controlled trials and observational studies averages around 0.15, suggesting RCTs tend to produce slightly larger effects

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The average effect size (Cohen's d) for psychological interventions is typically around 0.80

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An effect size of 0.2 is considered small, 0.5 medium, and 0.8 large according to Cohen's conventions

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In meta-analyses across education research, the average effect size is approximately 0.40

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A 2013 review found that effect sizes in social science research typically range between 0.15 and 0.25

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In health research, interventions with effect sizes of 0.2 are considered small, 0.5 medium, and 0.8 large

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The median effect size in clinical psychology studies is approximately 0.48

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In educational psychology, effect sizes for educational interventions average around 0.25

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Cohen's d effect size of 0.8 or above is typically considered a large effect

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The average effect size for psychotherapy outcomes is approximately 0.85

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Meta-analyses of behavioral interventions often report effect sizes in the range of 0.4 to 0.6

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The effect size for cognitive-behavioral therapy for depression is typically around 0.8

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In educational attainment studies, effect sizes of around 0.10 are considered small, 0.25 moderate, and 0.40 large

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Effect sizes in job training research typically range from 0.2 to 0.3, indicating modest effects

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The average effect size in organizational behavior studies is approximately 0.33

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Effect sizes for mindfulness-based interventions are commonly between 0.3 and 0.5, indicating moderate effects

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The typical effect size in marketing research is around 0.2, signifying small effects

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In medical research, a small effect size (Cohen's d = 0.2) can still translate to clinically significant improvements

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Large meta-analyses find that effect sizes for physical activity interventions typically range from 0.3 to 0.6

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The median effect size in systematic reviews of social and emotional learning programs is approximately 0.34

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Effect sizes in neuropsychological research generally fall between 0.3 and 0.7, with many interventions showing medium to large effects

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In online learning studies, effect sizes tend to be small to moderate, averaging around 0.26

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Effect sizes so far identified for behavioral weight loss interventions average about 0.27, indicating small to medium effects

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A systematic review reports that effect sizes for behavioral parent training are around 0.4, indicating moderate effects

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The effect size for social skills training programs in children generally ranges from 0.3 to 0.5, indicating moderate effects

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Effect sizes in digital health interventions for mental health are typically about 0.3 to 0.4, pointing to moderate effects

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Effect sizes in school-based reading interventions often approximate 0.25, considered a small to moderate effect

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In economic evaluations, an effect size of 0.2 is often used as a benchmark for small effects

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Research indicates that medium effect sizes around 0.5 are typical for workplace diversity training programs

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Effect sizes in psychotherapy for anxiety disorders often exceed 0.8, indicating large effects

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The typical odds ratio corresponding to a small effect size (d=0.2) is approximately 1.2

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Effect sizes in marketing email campaigns are often around 0.1 to 0.2, reflecting small effects

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In psychotherapy research, interventions with an effect size of 1.0 or higher are considered very large effects

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For physical health interventions, effect sizes greater than 0.5 are commonly interpreted as moderate to large

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The effect size of a typical school suspension program on student behavior averages around 0.2, signifying small effects

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In workplace interventions addressing burnout, effect sizes usually range from 0.4 to 0.6, indicating moderate effects

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In addiction treatment, effect sizes for medication alone often range from 0.3 to 0.5, showing moderate effects

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Effect sizes in interventions for improving classroom behavior often target around 0.3, indicating moderate impacts

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The effect size for public health campaigns on smoking cessation is typically around 0.2, reflecting small effects

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A large-scale meta-analysis found that school-based physical activity interventions yield an average effect size of 0.33, indicating a moderate effect

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Effect sizes for interventions in reducing childhood behavioral problems generally average around 0.55, indicating moderate to large effects

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In social work interventions, effect sizes are often around 0.3, indicating small to moderate effects

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The typical effect size for interventions targeting adult depression is near 0.8, suggesting large effects

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In marketing research, effect sizes for online ads typically range from 0.1 to 0.2, signifying small effects

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Effect sizes in behavioral economics experiments tend to fall between 0.2 and 0.4, indicating small to moderate effects

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Research shows that effect sizes for social media interventions are generally around 0.2, indicating small effects

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The median effect size in workplace safety training programs is approximately 0.4, reflecting moderate effects

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In mental health smartphone app interventions, effect sizes tend to average around 0.3, indicating moderate effects

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Key Highlights

The average effect size (Cohen's d) for psychological interventions is typically around 0.80
An effect size of 0.2 is considered small, 0.5 medium, and 0.8 large according to Cohen's conventions
In meta-analyses across education research, the average effect size is approximately 0.40
A 2013 review found that effect sizes in social science research typically range between 0.15 and 0.25
In health research, interventions with effect sizes of 0.2 are considered small, 0.5 medium, and 0.8 large
The median effect size in clinical psychology studies is approximately 0.48
In educational psychology, effect sizes for educational interventions average around 0.25
Cohen's d effect size of 0.8 or above is typically considered a large effect
The average effect size for psychotherapy outcomes is approximately 0.85
Effect sizes tend to be smaller in social and behavioral interventions compared to biomedical interventions
Meta-analyses of behavioral interventions often report effect sizes in the range of 0.4 to 0.6
The effect size for cognitive-behavioral therapy for depression is typically around 0.8
In educational attainment studies, effect sizes of around 0.10 are considered small, 0.25 moderate, and 0.40 large

Understanding the true impact of psychological and social interventions hinges on a key metric: effect size, which varies from small effects around 0.2 to large, transformative changes exceeding 0.8—highlighting the importance of this statistic in evaluating research outcomes across diverse fields.

Intervention Types and Effectiveness

Effect sizes tend to be smaller in social and behavioral interventions compared to biomedical interventions

Intervention Types and Effectiveness Interpretation

While social and behavioral interventions may showcase more modest effect sizes compared to their biomedical counterparts, this subtlety underscores their nuanced influence on human lives that often defies straightforward measurement.

Meta-Analyses and Systematic Reviews

The difference in effect sizes between randomized controlled trials and observational studies averages around 0.15, suggesting RCTs tend to produce slightly larger effects

Meta-Analyses and Systematic Reviews Interpretation

While randomized controlled trials generally yield somewhat larger effect sizes—about 0.15 more—this subtle difference underscores how study design nuances can gently tip the interpretive scale without dramatically altering conclusions.

Research Effect Sizes and Benchmarks

The average effect size (Cohen's d) for psychological interventions is typically around 0.80
An effect size of 0.2 is considered small, 0.5 medium, and 0.8 large according to Cohen's conventions
In meta-analyses across education research, the average effect size is approximately 0.40
A 2013 review found that effect sizes in social science research typically range between 0.15 and 0.25
In health research, interventions with effect sizes of 0.2 are considered small, 0.5 medium, and 0.8 large
The median effect size in clinical psychology studies is approximately 0.48
In educational psychology, effect sizes for educational interventions average around 0.25
Cohen's d effect size of 0.8 or above is typically considered a large effect
The average effect size for psychotherapy outcomes is approximately 0.85
Meta-analyses of behavioral interventions often report effect sizes in the range of 0.4 to 0.6
The effect size for cognitive-behavioral therapy for depression is typically around 0.8
In educational attainment studies, effect sizes of around 0.10 are considered small, 0.25 moderate, and 0.40 large
Effect sizes in job training research typically range from 0.2 to 0.3, indicating modest effects
The average effect size in organizational behavior studies is approximately 0.33
Effect sizes for mindfulness-based interventions are commonly between 0.3 and 0.5, indicating moderate effects
The typical effect size in marketing research is around 0.2, signifying small effects
In medical research, a small effect size (Cohen's d = 0.2) can still translate to clinically significant improvements
Large meta-analyses find that effect sizes for physical activity interventions typically range from 0.3 to 0.6
The median effect size in systematic reviews of social and emotional learning programs is approximately 0.34
Effect sizes in neuropsychological research generally fall between 0.3 and 0.7, with many interventions showing medium to large effects
In online learning studies, effect sizes tend to be small to moderate, averaging around 0.26
Effect sizes so far identified for behavioral weight loss interventions average about 0.27, indicating small to medium effects
A systematic review reports that effect sizes for behavioral parent training are around 0.4, indicating moderate effects
The effect size for social skills training programs in children generally ranges from 0.3 to 0.5, indicating moderate effects
Effect sizes in digital health interventions for mental health are typically about 0.3 to 0.4, pointing to moderate effects
Effect sizes in school-based reading interventions often approximate 0.25, considered a small to moderate effect
In economic evaluations, an effect size of 0.2 is often used as a benchmark for small effects
Research indicates that medium effect sizes around 0.5 are typical for workplace diversity training programs
Effect sizes in psychotherapy for anxiety disorders often exceed 0.8, indicating large effects
The typical odds ratio corresponding to a small effect size (d=0.2) is approximately 1.2
Effect sizes in marketing email campaigns are often around 0.1 to 0.2, reflecting small effects
In psychotherapy research, interventions with an effect size of 1.0 or higher are considered very large effects
For physical health interventions, effect sizes greater than 0.5 are commonly interpreted as moderate to large
The effect size of a typical school suspension program on student behavior averages around 0.2, signifying small effects
In workplace interventions addressing burnout, effect sizes usually range from 0.4 to 0.6, indicating moderate effects
In addiction treatment, effect sizes for medication alone often range from 0.3 to 0.5, showing moderate effects
Effect sizes in interventions for improving classroom behavior often target around 0.3, indicating moderate impacts
The effect size for public health campaigns on smoking cessation is typically around 0.2, reflecting small effects
A large-scale meta-analysis found that school-based physical activity interventions yield an average effect size of 0.33, indicating a moderate effect
Effect sizes for interventions in reducing childhood behavioral problems generally average around 0.55, indicating moderate to large effects
In social work interventions, effect sizes are often around 0.3, indicating small to moderate effects
The typical effect size for interventions targeting adult depression is near 0.8, suggesting large effects
In marketing research, effect sizes for online ads typically range from 0.1 to 0.2, signifying small effects
Effect sizes in behavioral economics experiments tend to fall between 0.2 and 0.4, indicating small to moderate effects
Research shows that effect sizes for social media interventions are generally around 0.2, indicating small effects
The median effect size in workplace safety training programs is approximately 0.4, reflecting moderate effects
In mental health smartphone app interventions, effect sizes tend to average around 0.3, indicating moderate effects

Research Effect Sizes and Benchmarks Interpretation

While effect sizes across disciplines reveal that most psychological and behavioral interventions tend to produce modest, often moderate improvements—say, around 0.25 to 0.50—it's a sobering reminder that even large-effect treatments (above 0.8) are the exception rather than the norm, highlighting both the incremental nature of scientific progress and the importance of measuring real-world impact beyond mere numbers.