Computing t Tests
I am choosing an independent-samples t test because I want to find out if the two groups are different from each other. My independent variable is the visualization therapy since I can manipulate it. My dependent variable is how long it takes the participants to fall asleep because it is what is affected during the experiment (Welkowitz, Cohen, & Lea, 2012). My alternate hypothesis states that the visualization treatment significantly decreases the amount of time to fall asleep for people who receive the treatment. Therefore, my null hypothesis states that the visualization treatment does not significantly decrease the amount of time to fall asleep for people who receive and do not receive the treatment. This is a one-tailed test because we are only interested in the results of the visualization therapy.
We have homogeneity of variance due to our p-value of equal variances assumed being 1.00. This is because it is greater than 0.05. It is important to know this because it lets us know if the groups are equal or not and therefore have not violated our homogeneity of variance (Welkowitz et al., 2012). An unequal variance affects our rate of Type I errors. The t value I was able to obtain in SPSS was 1.492. The degrees of freedom is 18 and I am able to determine it by using the formula:
$df = \ {(N}_{1} - 1) + \ {(N}_{2} - 1)$
$df = (10 - 1) + (10 - 1) = 18$
The p value I arrived at is 0.153 and I will retain the null hypothesis because the p value is greater than 0.05. I can conclude that there is no difference between those who took the visualization therapy to those who did not take the visualization therapy.