Mann Whitney U Test Calculator
Compares two independent groups through pooled ranks and reports a tie-corrected normal approximation. The form displays rank-sum U with tie-corrected normal approximation beside mann–whitney u test, using a worked condition that can be recalculated with the labeled inputs.
Set the comparison values in this example
Mann–Whitney U test
The question behind mann–whitney u test
The mann whitney u test page compares two independent groups through pooled ranks and reports a tie-corrected normal approximation.
Mann–Whitney U test is limited to the statistical quantity named by the result panel. The mann–whitney u test calculation does not silently add a population, time horizon, causal direction, or decision threshold that is absent from the fields.
Reading the mann whitney u test fields
- Group A: For mann–whitney u test, the displayed group a sequence is 12, 15, 14, 13, 16, 17. Preserve group a order when mann–whitney u test depends on pairing, lag, rank, or time position, and distinguish an observed zero from a missing group a entry.
- Group B: For mann–whitney u test, the displayed group b sequence is 18, 19, 16, 20, 21, 17. Preserve group b order when mann–whitney u test depends on pairing, lag, rank, or time position, and distinguish an observed zero from a missing group b entry.
The entries used for mann–whitney u test must refer to one coherent analysis condition. Combining incompatible populations, periods, or measurement definitions can produce valid mann–whitney u test arithmetic for a nonexistent study.
Working through the mann whitney u test formula
For mann–whitney u test, match every symbol in the relationship to a labeled field before substituting numbers. Mann–Whitney U test is reported in the scale implied by the inputs and formula.
While checking mann–whitney u test, use group a observations from one defined analysis set rather than totals copied from incompatible groups.
Checking the displayed example
The default mann–whitney u test condition is Group A = 12, 15, 14, 13, 16, 17, Group B = 18, 19, 16, 20, 21, 17.
The example produces the smaller U statistic, a continuity-corrected z value, and a two-sided p-value.
The live calculator reports Smaller U statistic 2 · Continuity-corrected z -2.4907104 · Two-sided p-value 0.01274882. Repeating one intermediate step from rank-sum U with tie-corrected normal approximation provides a fixed mann–whitney u test reference check for later code changes.
What the mann whitney u test arithmetic assumes
The test concerns stochastic ordering; describing it purely as a median test requires additional shape assumptions.
For mann whitney u test, a p-value measures compatibility with a stated null model; it is not the probability that the null hypothesis is true and it does not measure practical importance.
Reading mann–whitney u test in context
When interpreting mann whitney u test, pair the test result with the effect direction, effect size, uncertainty, sampling design, and the rule used for one-sided or two-sided inference.
As a second check for mann–whitney u test, outliers, ties, ordering, and missing entries can affect mann–whitney u test even when the number of observations stays unchanged.
For a related comparison, continue with bartlett test, wilcoxon signed rank test, and levene test.
Testing how stable mann–whitney u test is
Change group a while holding the remaining entries fixed, then state why the direction and size of the mann–whitney u test change are plausible from rank-sum U with tie-corrected normal approximation.
Repeat the mann–whitney u test exercise with group b. If a modest defensible change materially alters the interpretation, report both conditions rather than presenting that mann–whitney u test scenario as exact.
Common failure modes for mann–whitney u test
Before accepting mann–whitney u test, compare every entered value with its label, unit, and allowed domain after reading the printed relationship from left to right.
For mann–whitney u test, do not substitute zero for an unobserved value; missingness and a measured zero describe different data.
Another mann–whitney u test failure occurs when a rounded output is reused as though it were the original measurement. Carry guard digits through calculations that depend on mann–whitney u test, then round only the reported value.
Rebuilding this mann whitney u test calculation later
Report mann–whitney u test using rank-sum U with tie-corrected normal approximation, followed by the entered values, units, exclusions, and analysis date. Name the mann–whitney u test population or dataset boundary instead of leaving it implicit.
Keep the full calculator output with the record, including Smaller U statistic 2 · Continuity-corrected z -2.4907104 · Two-sided p-value 0.01274882. A later mann–whitney u test review can then distinguish a changed input from a different convention or software implementation.
Questions about mann–whitney u test
Why could another program report a different mann–whitney u test?
A different convention for rounding, tails, ties, interpolation, parameterization, or missing values can change mann–whitney u test. Compare the printed mann–whitney u test formula and its input definitions before treating either output as wrong.
What does mann–whitney u test represent on this page?
It is the quantity produced by rank-sum U with tie-corrected normal approximation from the displayed group a, group b. This page compares two independent groups through pooled ranks and reports a tie-corrected normal approximation.
What should be saved with mann–whitney u test?
Save the entered values and units for group a, group b, along with the analysis date, exclusions, software or formula version, and the relationship rank-sum U with tie-corrected normal approximation. That record is sufficient to rebuild this specific mann–whitney u test calculation.