Question

4. A researcher wants to know whether supplements affect how long vampires can go without requiring human blood. She took one sample of vampires (n = 13). Half received a placebo first and the supplement second, while the other half received the supplement first and the placebo second. She then recorded how many days the vampires could go without consuming human blood for each condition. The goal of the study was to see whether there would be any difference between supplement and placebo. Conduct the appropriate t-test for these data (α =0.05) and calculate a confidence interval (99%) as a measure of effect size. Assume all assumptions for the test are met. (See table below for sample data.)

With placebo	With supplement	D
M =10.46	M =14.23	M =−3.77
SS =187.23	SS =114.31	SS =138.31
n =13	n =13	n =13
SD =3.95	SD =3.09	SD =3.39

Given all of this informations, the researchers obtained a t test statistic of t_obtained =−4.01.

They also found an effect size of a 99% CI[−6.64,−0.9].

Answer 1