Class Size Effect Size Calculator (Hattie d)

Estimate standardised effect size (Cohen's d) of class size reduction on student achievement, based on Hattie's Visible Learning synthesis. Apply threshold analysis: d ≥ 0.40 is the 'hinge point' above which interventions have meaningful impact.

Data set — comma or newline separated
Statistical Results — n = 8
Count (n)8
Sum (Σx)40
Min2
Max9
Range7
Q14
Q35.5
IQR1.5
Mean (μ)5
Median4.5
Mode4
Pop. Variance (σ²)4
Pop. Std Dev (σ)2
Sample Variance (s²)4.571428571
Sample Std Dev (s)2.138089935
Skewness0.65625
Excess Kurtosis-0.21875
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How It Works

Estimate standardised effect size (Cohen's d) of class size reduction on student achievement, based on Hattie's Visible Learning synthesis. Apply threshold analysis: d ≥ 0.40 is the 'hinge point' above which interventions have meaningful impact

Each component has a specific meaning:

  • Hattie's Visible Learning synthesis — The hattie's visible learning synthesis recorded for the scenario being assessed.

Note: Interpret the class size effect d result against the thresholds and context described above.

How to Use

Enter the Hattie's Visible Learning synthesis for the scenario you are assessing. Estimate standardised effect size (Cohen's d) of class size reduction on student achievement, based on Hattie's Visible Learning synthesis. Apply threshold analysis: d ≥ 0.40 is the 'hinge point' above which interventions have meaningful impact. Use the class size effect d result to inform your calculation.

Frequently Asked Questions