Example 18. Kruskal-Wallis Procedure: Psychotherapeutic Attraction Data

In counseling and psychotherapy of subjects, the beneficial effects of pretherapy training has been discussed. Four different approches to pretherapy training are (a) control (no training), (b) therapeutic reading (TR), which involves indirect learning, (c) vicarious therapy pretraining (VTP), which involves videotaped vicarious learning, and (d) group, role induction interview (RII), which involves direct learning. It is useful to compare the effectiveness of these approaches on the response variable, psychotherapeutic attraction.

Source: Sauber, S.R. (1971). Approaches to precounseling and therapy training: an investigation of its potential influence on process outcome. Ph.D. Thesis, Florida State University.

Table 18: Pretherapy Data

Control  Reading (TR)  Videotape (VTP)  Group (RII)
      0             0                0            1
      1             6                5            5
      3             7                8           12
      3             9                9           13
      5            11               11           19
     10            13               13           22
     13            20               16           25
     17            20               17           27
     26            24               20           29

Questions:

1. Implement a distribution-free procedure to check whether there exist differences in location due to the different treatments.

Keywords: Kruskal-Wallis procedure, scores