Question

8. Desert iguanas are thought to use their tongues to obtain information about their environment by sampling odours that may be important for their survival and reproductive success. Pedersen (1988) studied the rates of tongue extrusions in desert iguanas who were exposed to sands collected from a = 5 different environments. These environments consisted of a1 = clean sand, a2 = sand from an iguana’s home cage, a3 = sand from cages housing other iguanas, a4 = sand from cages housing western whiptail lizards, and a5 = sand from cages housing desert kangaroo rats. (The latter two species are frequently seen in close contact with desert iguanas in their natural habitat). A total of n = 10 iguanas served in the experiment. Each was tested in each condition on successive days; the order of testing was randomly determined for each animal. The iguanas were videotaped during each 10-minute test session; the response measure was the number of tongue extrusions observed during each test session.

Subject	a1	a2	a3	a4	a5
1	8	5	14	10	16
2	2	2	0	2	4
3	1	0	2	1	3
4	4	3	3	5	6
5	0	0	0	0	0
6	2	5	3	5	12
7	2	1	1	2	5
8	0	0	0	3	11
9	0	1	0	0	3
10	3	2	1	2	8

Answer 1

First thing to obsrve that we need to test mean tongue extrusions in five different environments (a1, a2, a3, a4 and a5). So, we should go for repeated measure ANOVA but as distribution of all five are not known so we can't go for ANOVA therefore we looked for non-parametric alternative and we identified Friedman test as non-parametric alternative of repeated measure ANOVA.

Data is entered in SPSS data file as below

Then

Click Analyze > Nonparametric Tests > Legacy Dialogs > K Related Samples...  

Transfer all five variables to Test Variable Box

Check Box on Friedman,

You will get following output

Since Asymp. Sig (0.000) is less than 0.05 we reject the null hypothesis of equality of all five means. So conclude that mean tongue extrusions are different in five environments (a1, a2, a3, a4 and a5).