Question

4. Practice with Tukey's HSD

To investigate the maternal behavior of laboratory rats, a researcher moves a rat pup a fixed distance from its mother and record the time (in seconds) required for the mother to retrieve the pup to the nest. We run a study with 5-, 10-, and 15-day-old pups. We are interested in examining whether there is a change in maternal behavior (i.e., retrieval of the pups) over time. (Higher numbers indicate that the mother is less concerned about her pups!) Here are some summary data for these three groups:

5-day-old pups (n = 6)

M = 17 seconds

10-day-old pups (n = 6)

M = 22 seconds

15-day-old pups (n = 6)

M = 42 seconds

An ANOVA reveals a significant difference across the three groups, F(2, 15) = 42.8, p < .05. The researcher decides to use Tukey's HSD to draw more specific conclusions. If Tukey's HSD = 5.8 in this case, which of the following conclusions are valid? Check all that apply.

--There is no significant difference in maternal behavior for rat pups of 10 and 15 days of age.

--Retrieval time for rat pups of 15 days of age is significantly longer than for those 5 days of age.

--Retrieval time for rat pups of 10 days of age is significantly longer than for those 5 days of age.

--Retrieval time for rat pups of 15 days of age is significantly longer than for those 10 days of age.

--There is no significant difference in maternal behavior for rat pups of 5 and 15 days of age.

--There is no significant difference in maternal behavior for rat pups of 5 and 10 days of age.

Answer 1

The degrees of freedom for Tukey HSD will be 15 and the critical value for Tukey HSD using Q table(which provides critical value for Tukey HSD) at a 5% level of significance is 3.67.

Since the critical value is less than Tukey’s HSD (5.8) we will conclude that there exists a significant difference.

Therefore, the correct options will be:

--Retrieval time for rat pups of 15 days of age is significantly longer than for those 5 days of age.

--Retrieval time for rat pups of 10 days of age is significantly longer than for those 5 days of age.

--Retrieval time for rat pups of 15 days of age is significantly longer than for those 10 days of age.

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