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Function Reference: friedman

statistics: p = friedman (x)
statistics: p = friedman (x, reps)
statistics: p = friedman (x, reps, displayopt)
statistics: [p, atab] = friedman (…)
statistics: [p, atab, stats] = friedman (…)

Performs the nonparametric Friedman’s test to compare column effects in a two-way layout. friedman tests the null hypothesis that the column effects are all the same against the alternative that they are not all the same.

friedman requires one up to three input arguments:

  • x contains the data and it must be a matrix of at least two columns and two rows.
  • reps is the number of replicates for each combination of factor groups. If not provided, no replicates are assumed.
  • displayopt is an optional parameter for displaying the Friedman’s ANOVA table, when it is ’on’ (default) and suppressing the display when it is ’off’.

friedman returns up to three output arguments:

  • p is the p-value of the null hypothesis that all group means are equal.
  • atab is a cell array containing the results in a Friedman’s ANOVA table.
  • stats is a structure containing statistics useful for performing a multiple comparison of medians with the MULTCOMPARE function.

If friedman is called without any output arguments, then it prints the results in a one-way ANOVA table to the standard output as if displayopt is ’on’.

Examples:

 
 load popcorn;
 friedman (popcorn, 3);
 
 [p, anovatab, stats] = friedman (popcorn, 3, "off");
 disp (p);

See also: anova2, kruskalwallis, multcompare

Source Code: friedman

Example: 1

  

 load popcorn;
 friedman (popcorn, 3);

              Friedman's ANOVA Table
Source            SS      df        MS    Chi-sq    Prob>Chi-sq
---------------------------------------------------------------
Columns         99.7500     2    49.8750    13.76    0.0010
Interaction      0.0833     2     0.0417  
Error           16.1667    12     1.3472
Total          116.0000    17

Example: 2

  

 load popcorn;
 [p, atab] = friedman (popcorn, 3, "off");
 disp (p);

1.0289e-03