RANKREL(1)

NAME
rankrel - rank order statistics for related samples

SYNOPSIS
rankrel [-ry] [-c maxcases] [names]

DESCRIPTION
rankrel analyses data from ordinally ranked data obtained from related/matched samples. The input consists of scores from several samples, conditions, or groups. Each condition's data are in a separate column. The scores need not be ranks; they will be ranked by the program. For each condition, the number of scores, extrema and quartiles are reported. Conditions are compared for equality of location using the sign test, the Wilcoxon signed-ranks test, and the Friedman two-way analysis of variance of ranks. A matrix of Spearman rank-order correlation coefficients (rho) is printed.

The sign test and the Wilcoxon test are only used when there are two conditions. When there are fewer than 25 paired cases that are different, the exact binomial probability is computed; for larger N, the normal approximation is used.

  Probability of Obtained Statistics
Functions computing exact probabilities of Wilcoxon and Friedman could not be found when the program was written, so for small samples, statistical tables at the back of a text should be consulted. For large samples, normal and Chi-square approximations are adequate.

OPTIONS
[c maxcases] Set the maximum number of input cases. Use the -L option to see the default. [r] Request a report of average ranks for conditions. [s] Stop significance tests from printing. This option is useful when the Spearman rho values are of primary interest. [y] When computing the normal approximation for the probability of the Wilcoxon test, Yates' correction for continuity is applied. This option stops its use. There are no cases where Yates' correction should not be used, but the option is useful to check textbook examples for accuracy.

EXAMPLE

The following data are from Siegel, page 79. The command names the conditions "school" and "home."
	> rankrel school home
	82	63
	69	42
	73	74
	43	37
	58	51
	56	43
	76	80
	65	62

sign test: 0.144531 (one-tailed)
Wilcoxon T = 4, N = 8
	p approximated with z: .026892 (one-tailed)
	tabled critical value for T for one-tailed p = .025: 4
Friedman R = 2
Spearman Rank Correlation (rho) = .786

LIMITS
Use the -L option to determine the program limits.

MISSING VALUES
Cases with missing data values (NA) are counted but not included in the analysis.

SEE ALSO
pair(1), regress(1), and anova(1) perform the normal-theory parametric counterparts to this non-parametric, distribution-free analysis. To see a scatterplot of ranks, the ranksort(1) filter can be used as a pre-processor for the pair(1) plotting option. rankind(1) analyses ordinal data for independent conditions.

Siegel, S. (1956) Nonparametric Statistics for the Behavioral Sciences. New York: McGraw-Hill.

WARNING
When the program advises to check a table for exact probabilities of significance tests, it may still compute approximate values. These approximations should not be used for serious work.