Sample Size Calculator

When to use

• Use it for educational, planning, or preliminary research review involving sample size calculator.
• Use it when the available data and assumptions match the stated method rather than when a full statistical modelling workflow is required.
• Use it to produce transparent intermediate values, copyable summaries, and downloadable CSV or JSON result artifacts.

How to use

1. Enter manual values or load a local CSV where the tool supports CSV input.
2. Check method options such as alpha, confidence level, variance convention, group mode, or selected columns.
3. Click Calculate Sample Size; do not interpret defaults or CSV previews as final results.
4. Review the result summary, assumptions, warnings, visual, table, examples, FAQs, and references before using the output.

Inputs

Manual input

Paste numeric values, paired values, count tables, group rows, or item matrices in the format shown by the input control.

CSV input

This tool uses summary or manual inputs and does not require CSV file loading.

Alpha or confidence

Inference tools use the selected threshold only after calculation and report it beside the result.

Method

The calculator applies normal-approximation planning formulas and rounds final required sample size upward.

Notation

Interpretation

• Read the reported statistic with the assumptions and selected method, not as a standalone approval decision.
• For p-values, ScholarTool reports whether evidence is sufficient to reject the null at alpha; it does not accept the null or prove a hypothesis.
• For intervals and estimates, the output describes plausible values under assumptions and should be checked against study design.

Effect-size guidance

• Effect sizes and interval widths should be considered alongside p-values when available.
• Magnitude, uncertainty, measurement quality, and domain relevance matter more than a single threshold.
• Small samples, non-independent observations, and poor measurement quality can make effect-size interpretation unstable.

Worked examples

Assumptions

• Inputs are finite numeric values after parsing, with missing or invalid values handled according to the selected workflow.
• Planning formulas are normal-approximation estimates.
• The selected margin, power, and nonresponse assumptions are defensible for the study design.

Practical guidance

• Keep the original data and analysis plan available so the calculated output can be audited.
• Verify data cleaning, coding, missing values, and grouping decisions before interpreting the final result.
• Use validated statistical software or a qualified analyst when the study design is complex or decisions are high stakes.

Common mistakes

• Using p = 0.5 without recognizing it is conservative.
• Ignoring nonresponse or dropout.

Limitations

• Power approximations are planning estimates.
• Complex survey designs and clustering are out of scope.

Related workflow links