Research Tools

Free, accurate statistical calculators for psychology, research methods, and academic work. All calculations happen locally in your browser.

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Statistical Calculators

Reliability

Cronbach's Alpha Calculator

Calculate Cronbach's alpha to assess the internal consistency reliability of a scale or questionnaire.

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Effect Size

Cohen's d Calculator

Calculate Cohen's d effect size for comparing two independent group means, with Hedges' g correction.

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Study Design

Sample Size Calculator

Calculate the required sample size for estimating a population proportion with a given confidence level and margin of error.

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Hypothesis Testing

t-Test Calculator (Independent & Paired)

Perform independent samples Student's t-test, Welch's t-test, and paired t-test with exact p-values, 95% confidence intervals, Cohen's d, and APA 7th write-ups.

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Planned Calculators

In Development

The following statistical modules are currently being developed and validated against R and SPSS reference outputs.

Pearson Correlation CalculatorCorrelation

Spearman Correlation CalculatorCorrelation

One-Way ANOVA CalculatorHypothesis Testing

Chi-Square Test CalculatorHypothesis Testing

Confidence Interval CalculatorEstimation

Statistical Power CalculatorStudy Design

Z-Score CalculatorDescriptive Statistics

Standard Error CalculatorDescriptive Statistics

APA Table GeneratorReporting

Likert Scale ScoringData Preparation

Reverse Scoring CalculatorData Preparation

Regression CalculatorModeling