A health psychologist investigated whether a virtual-reality (VR) guided-breathing program is effective in reducing chronic lower-back pain intensity. Participants were randomly allocated to either a VR Breathing group ( $N_a = 6$ ) or an Audiobook Control group ( $N_b = 9$ ). Pain intensity was rated daily using an ordinal scale. The researcher conducted a Mann-Whitney U test and calculated an observed value of $U = 12$ .

Table 1: Critical values for the Mann-Whitney U test

$N_a$	$N_b = 5$	$N_b = 6$	$N_b = 7$	$N_b = 8$	$N_b = 9$	$N_b = 10$	$N_b = 11$	$N_b = 12$
$\le 0.05$ (one-tailed)
6	6	8	11	13	15	17	19	21

Using the critical values for the Mann-Whitney U test in Table 1, explain whether the VR breathing program is effective in reducing pain intensity scores.

Table 1: Critical values for the Mann-Whitney U test

$N_a$	$N_b = 5$	$N_b = 6$	$N_b = 7$	$N_b = 8$	$N_b = 9$	$N_b = 10$	$N_b = 11$	$N_b = 12$
$\le 0.05$ (one-tailed)
6	6	8	11	13	15	17	19	21

Using the critical values for the Mann-Whitney U test in Table 1, explain whether the VR breathing program is effective in reducing pain intensity scores.

Research methods and skills

Question 8

Markscheme

Research methods and skills

Question 8

Markscheme

Research methods and skills

Question 8

Research methods and skills Questions

Research methods and skills

Question 8

Research methods and skills Questions