All calculators
Start with the calculator that matches your statistical question. Each Statoma page pairs the calculation with interpretation, formulas, worked examples, and common mistakes.
Choose By Question
A calculator should be chosen from the design of the question, not from the result you hope to see. Use the guide below to match the data structure and reporting goal to the right Statoma workflow.
Compare Means
Is a sample mean or mean difference different from a reference value?
Use this when the outcome is numeric and the question is about a mean, paired mean difference, or two independent group means.
Open the t-test calculatorConvert A Test Statistic
Do you already have a z, t, chi-square, or F statistic?
Use this when the statistic and degrees of freedom are known and the main task is choosing the correct distribution and tail.
Open the p-value calculatorEstimate Uncertainty
Do you need a range of plausible values around an estimate?
Use this for means, proportions, differences in means, and differences in proportions when uncertainty matters more than a single threshold.
Open the confidence interval calculatorPlan Data Collection
How many observations should be collected before analysis?
Use this before collecting data to connect precision, power, detectable effects, and planning assumptions.
Open the sample size calculatorCheck Categorical Counts
Do observed category counts differ from expected counts or table independence?
Use this for goodness-of-fit questions and two-way contingency tables built from categorical counts.
Open the chi-square calculatorWhat To Check Before You Calculate
Before entering numbers, identify the observational unit, the outcome type, the comparison being made, and the assumptions the method requires. A t-test assumes a question about means. A confidence interval assumes the estimate and standard error are meaningful for the sampling design. A chi-square test assumes categorical counts with appropriate expected counts. Those design checks matter as much as the final arithmetic.
Statoma calculators currently use summary statistics rather than uploaded datasets. That keeps the tools focused and transparent: you bring the relevant sample means, standard deviations, counts, margins, or test statistics, and the page shows how the result is built from those values. If your analysis needs modeling choices, transformations, clustering, survey weights, missing-data handling, or multiple comparisons, treat these calculators as a teaching reference rather than the whole analysis.
What Comes Next
The calculator set is the foundation. The Statoma statistics topics index will add longer guides that explain ideas like p-values, statistical power, confidence intervals, and categorical tests before users choose a specific calculator. Those guides will link back into this index so conceptual learning and calculation stay connected.