ANOVA-ONE-WAY-VARIABLES (IV DV &OPTIONAL (SCHEFFE-TESTS-P T)
CONFIDENCE-INTERVALS)
Performs a one-way analysis of variance (ANOVA) on the input data, which should be two equal-length sequences: `iv' is the independent variable, represented as a sequence of categories or group identifiers, and `dv' is the dependent variable, represented as a sequence of numbers. The `iv' variable must be ``sorted,'' meaning that AAABBCCCCCDDDD is okay but ABCDABCDABDCDC is not, where A, B, C and D are group identifiers. Furthermore, each group should consist of at least 2 elements. The significance of the result indicates that the group means are not all equal; that is, at least two of the groups have significantly different means. If there were only two groups, this would be semantically equivalent to an unmatched, two-tailed t-test, so you can think of the one-way ANOVA as a multi-group, two-tailed t-test. This function returns five values: 1. an ANOVA table; 2. a list a group means; 3. either a Scheffe table or nil depending on `scheffe-tests-p'; and 4. an alternate value for SST. 5. a list of confidence intervals in the form `(,mean ,lower ,upper) for each group, if `confidence-intervals' is a number between zero and one, giving the kind of confidence interval, such as 0.9. The fourth value is only interesting if you think there are numerical accuracy problems; it should be approximately equal to the SST value in the ANOVA table. This function differs from `anova-one-way-groups' only in its input representation. See the manual for more information.