This week's graded assignment is an application of the repeated measures ttest, which involvesassessing the same group of individuals on two measures. The research setting is an aviationmaintenance, repair, and overhaul (MRO) facility, and the objective is to assess the effect a stress management initiative has on reducing employees' stress level. The rationale for the study isgrounded in the belief that employee stress could lead to increased feelings of rushing tocomplete a maintenance task, frustration, fatigue, and complacency, all of which could lead tomaintenance errors.

Toimplement thestudy,aresearcherpre-assessedemployees'stresslevelusingtheStress subscale of Fogarty's (2005) Maintenance Environment Survey. This 9-item subscaleassessesparticipants'perceivedfeelingsandconsequencesabouttheirstressandwhatcontributes to it. A sample item is, "The demands of my work interfere with my home and familylife." Items are scored using a traditional 5-point Likert scale ranging from 1 = Strongly Disagreeto 5 = Strongly Agree. Thus, overall scores could range from 9 to 45, with higher aggregatescoresreflecting higher levels of stress.

Following the pre-assessment, employees then engaged in various stress managementactivities for 1 month. These included a 30-minute extended lunch break each day, access to freeonsite mental health counseling, a 1-hour after-work social event every Friday afternoon, and a30-minute stress-reduction strategies workshop that was scheduled at various times each day toaccommodate employees' different schedules. At the end of the study period, employees werepost-assessed using the same instrument. The corresponding data are located in the Excel file"Week 8 Graded Assignment Data." You are to import this data set into your statistical softwareprogramand do the following (see also the correspondingGuided Example):

1. Pre-DataAnalysis

1. What is the research question and corresponding operational definitions?
2. Whatis the research methodology/design andwhyis this methodology appropriate?
3. Conduct an a priori power analysis to determine the minimum sample size needed. Is thegiven data set sufficient relative to this minimum sample size? In what way do you thinkthesizeof the given samplewillimpact the results?

2. DataAnalysis

UsingthedatafromtheExcel file,conductahypothesistestas follows:

1. Formulatethenullandalternativehypothesesinsymbols andwords.
2. Determinethetestcriteria.
3. Testfortheassumptionsoftherepeated measuresttest.
4. Runtheanalysisandrecordtheresults.
5. Make a decision to reject or fail to reject the null hypothesis and write a concludingstatement.

3. Post-DataAnalysis

1. Determineandinterprettheestimatedeffect size,d.
2. Determineandinterpretthepowerofthestudy.
3. Determineandinterpretthe95%confidenceinterval.
4. Presentatleastthree plausibleexplanationsfortheresults.
5. Explain how this study could be implemented as a between-groups design. From whichdesignbetween-groups vs. within-groupdo you think the results would be morecredible?Why?