The one-sample t
test discussed in Chapter 6 requires that you know the population mean.
It is unusual to have this information, so most studies compare two
samples instead. Each sample measures a different condition of the
independent variable.Before conducting a study, it is important to know if you would need to conduct a matched-samples ttest or an independent-samples ttest.
Independent samples consist of two groups of different people. One
group has been randomly selected and is not specifically tied to who is
in the other group. Matched samples are groups that are deliberately
selected to be similar to each other (matched pairs) or they are the
same people in both groups (repeated measures). For example, you might
want to select two groups that have similar heights. If height could
affect the experiment, it could be best to match the groups on that
variable. This Assignment will allow you to convey your understanding of
the basic concepts related to ttesting and will allow you to practice setting up and conducting an inferential parametric test in SPSS.Scenario: Imagine
you are a researcher who believes that a relaxation technique involving
visualization will help people with mild insomnia fall asleep faster.
You randomly select a sample of 20 participants from a population of
mild insomnia patients and randomly assign 10 to receive visualization
therapy. The other 10 participants receive no treatment. You
then measure how long (in minutes) it takes participants to fall asleep.
Your data are below. The numbers represent the number of minutes each
participant took to fall asleep. No Treatment (X1) Treatment (X2) 22 19 18 17 27 24 20 21 23 27 26 21 27 23 22 18 24 19 22 22 Assignment:To complete this Assignment, submit by Day 7 a response to each of the following:Explain whether you chose to use an independent-samples ttest or a matched-samples ttest. Provide a rationale for your choice.Identify the independent and dependent variables.Knowing
you believe the treatment will reduce the amount of time to fall
asleep, state the null and alternate hypotheses in words (not formulas).Explain whether you would use a one-tailed or two-tailed test and why.Explain
whether you have homogeneity of variance, and explain how you know.
Explain why it is important to know if you have homogeneity of variance.Identify the obtained t value for this data set using SPSS.Identify the degrees of freedom and explain how you determined it.Identify the p value.Explain whether you should retain or reject the null hypothesis and why.Explain what you can conclude about the effectiveness of visualization therapy.Submit
three documents for grading: your text (Word) document with your
answers and explanations to the application questions, your SPSS Data
file, and your SPSS Output file.Provide an APA reference list.Resources:ReadingsHeiman, G. (2015). Behavioral sciences STAT 2 (2nd ed). Stamford, CT: Cengage.. Chapter 8, “Hypothesis Testing Using the One-Sample t-test” (pp.126-138)Chapter 9, “Hypothesis Testing Using the Two-Sample t-test” (pp.140-158)Chapter 9 Review Card (p. 9.4)MediaStatsLectures. (2011a). SPSS – Dependent samples t-test [Video file]. Retrieved from http://www.youtube.com/watch?v=DzitbJHIBQMNote:The approximate length of this media piece is 4 minutes. This resource can help you determine a dependent-samples t test from sample data in SPSS.StatsLectures. (2011c). SPSS – Independent samples t-test [Video file]. Retrieved from http://www.youtube.com/watch?v=VUUfBWlziIUNote:The approximate length of this media piece is 5 minutes. This resource can help you conduct an independent-sample t test from sample data in SPSS.