Research Guide
Research Guides
Practical guides that explain the methods behind the calculators and link straight to the tools that implement them.
How to Choose the Right Statistical Test
A practical framework for picking the right statistical test: start from your research question, data type and study design, then check the assumptions.
Sample Size and Margin of Error: A Practical Guide
How sample size controls margin of error, the formulas behind both, the finite-population correction, and the practical caveats researchers should not skip.
Understanding P-Values and Statistical Significance
What a p-value actually means, what it does not mean, the role of the significance level, and why the field is moving away from the 0.05 bright line.
Confidence Intervals Explained
What a confidence interval is, how to interpret the 95% level correctly, how to calculate one for a mean or a proportion, and what changes its width.
Correlation vs Regression
The difference between measuring a linear association (correlation) and modelling a relationship to make predictions (regression), and how R² connects them.
T-Test vs Z-Test vs ANOVA
When to use a z-test, a t-test or an ANOVA, the assumptions behind each, and how the tests relate — including why F equals t² for two groups.
How to Calculate NPS
The Net Promoter Score formula, how to classify promoters, passives and detractors, a worked example, and the caveats about small samples and timing.
Survey Research Statistics: A Practical Guide
The core statistics every survey researcher should understand — response, completion and incidence rates, sample size, margin of error and significance — and how they fit together.