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📊 How to Choose a Statistical Test

Turn a research question into a defensible statistical test by matching variables, group structure, dependence, study design, and uncertainty.

lessons

~20 min

to learn

🔬 Science

subject

Adults

level

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What you’ll learn

Frame the questionTurn a research claim into a difference, association, prediction, or distribution question and classify its variables.The research question, variable roles, and group structure come before the test name.
Choose the analysisMatch group structure, pairing, categorical counts, or numerical relationships to an analysis family.The design and measurement level narrow the candidate analyses.
Check and reportUse diagnostics and study design to choose a defensible model and communicate its limits.A defensible report explains fit, magnitude, uncertainty, and what the result cannot establish.

Questions this course answers

A number used only as a patient label should be treated as what kind of variable?

The digits are labels, not measured amounts, so arithmetic comparisons have no meaning.

Why is an overall ANOVA useful before comparing many group pairs?

The overall test addresses whether there is evidence of any mean difference; follow-up comparisons still need care.

Which design calls for analyzing within-pair differences?

Repeated measurements on the same people are linked, so the change within each person is the relevant unit.

Put the main selection steps in a useful order.

The question determines the comparison, variable types narrow the candidates, design determines dependence, and diagnostics refine the choice.

Why should a report include an effect size and confidence interval alongside a p-value?

A small p-value can accompany a trivial effect in a large sample, and a wide interval can reveal that the estimate remains uncertain.

Grounded in trusted sources

NIST/SEMATECH e-Handbook of Statistical Methods, What are statistical tests?: https://www.itl.nist.gov/div898/handbook/prc/section1/prc13.htm
NIST/SEMATECH e-Handbook of Statistical Methods, EDA Assumptions: https://www.itl.nist.gov/div898/handbook/eda/section2/eda2.htm
NIST/SEMATECH e-Handbook of Statistical Methods, Product and Process Comparisons: https://www.itl.nist.gov/div898/handbook/prc/section1/prc1.htm
Penn State University STAT 200, Choosing a Statistical Test: https://online.stat.psu.edu/stat200/lesson/7
Penn State University STAT 200, Causal Conclusions: https://online.stat.psu.edu/stat200/lesson/1/1.4/1.4.2
UCLA Institute for Digital Research and Education, Choosing the Correct Statistic: https://stats.oarc.ucla.edu/other/mult-pkg/whatstat/
Wikimedia Commons MediaWiki API image records: https://commons.wikimedia.org/w/api.php

Every Wunder lesson is built from real, reputable sources — never invented.

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