labkit.biosignal.compareGroups

Description

Calculates descriptive statistics for each group and a two-sided Welch t-test for every pair of groups. Welch's test does not assume equal variances. Group order follows the first occurrence of each label in groups.

Rows with a nonfinite measurement or a blank group label are discarded before calculation. A pairwise row is still returned when either group has fewer than two observations or the estimated standard error is zero; its test statistic, degrees of freedom, and p-value are NaN.

Inputs

values

Numeric vector of measurements.

groups

Vector of labels accepted by string, such as a string array, cell array of character vectors, or categorical array. It must contain one label for each element of values.

Outputs

result

Structure with summary and pairwise tables.

Output Fields

summary

One row per group. Columns are Group, N, Mean, Std, Median, Min, and Max.

pairwise

One row per unique group pair. Columns are GroupA, GroupB, MeanDifference, T, DF, and P. MeanDifference is mean(GroupA) minus mean(GroupB); P is the two-sided Welch-test p-value.

Failure Behavior

Groups with fewer than two finite observations, or with zero estimated standard error, retain a pairwise row with NaN test statistics. values and groups must contain the same number of elements; incompatible input shapes or values that cannot be converted to numeric/text raise the originating MATLAB error.

Example

values = [4.8 5.1 5.0 6.2 6.0 6.4];
groups = ["control" "control" "control" "treated" "treated" "treated"];
result = labkit.biosignal.compareGroups(values, groups);