To demonstrate flavor aversion learning (that is, learning to dislike a flavor that is associated with becoming sick), researchers gave one group of laboratory rats an injection of lithium chloride immediately following consumption of saccharin-flavored water. Lithium chloride makes rats feel sick. A second control group was not made sick after drinking the flavored water. The next day, both groups were allowed to drink saccharin-flavored water. The amounts consumed (in milliliters) for both groups during this test are given below.

Amount Consumed
by Rats That Were
Made Sick (n = 4) Amount Consumed
by Control Rats
(n = 4)
5 12
2 8
4 11
3 7
(a) Test whether or not consumption of saccharin-flavored water differed between groups using a 0.05 level of significance. State the value of the test statistic. (Round your answer to three decimal places.)

State the decision to retain or reject the null hypothesis.

Retain the null hypothesis.
OR Reject the null hypothesis.

(b) Compute effect size using eta-squared (η2). (Round your answer to two decimal places.)
η2 =

a) Test whether or not consumption of saccharin-flavored water differed between groups using a 0.05 level of significance. State the value of the test statistic. (Round your answer to three decimal places.)

Here, we have to use the two sample t test for the population mean.

H0: µ1 = µ2 versus Ha: µ1 ≠ µ2

We are given alpha = 0.05

Test statistic = t = (X1bar – X2bar) / sqrt[(S1^2/N1)+(S2^2/N2)]

Test statistic = t = (3.5 – 9.5)/sqrt[(1.29^2/4)+(2.38^2/4)]

Test statistic = t = -4.433

State the decision to retain or reject the null hypothesis.

Here, df = 4+4 – 2 = 8 – 2 = 6

P-value = 0.004

Alpha value = 0.05

P-value < Alpha value

So, reject the null hypothesis.

(b) Compute effect size using eta-squared (η2). (Round your answer to two decimal places.)

η2 =

Effect size = (X1bar – X2bar)/Spooled

Spooled = sqr(((4-1)*1.29^2+(4-1)*2.38^2)/(4+4-2)) = 1.914223

Effect size = (9.5 – 3.5) / 1.914223 = 3.13443

Step-by-step explanation:

See attached picture.