BTM8107-8 Week 2 Understanding and Exploring Assumptions Correct Answers

Week 2 solutions on statistical assumptions and hypothesis testing.

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BTM8107-8Week 2Understanding andExploring Assumptions CorrectAnswers1.Why do we care whether the assumptions required for statistical tests are met? (Tip: You might alsowant to write your answer on a note card you paste to your computer.)2. Open the data set that you corrected in Activity #1 for DownloadFestival.sav. You will use the followingvariables: Day1, Day2, and Day3 (hygiene variable for all three days). Create a simple histogram for eachvariable. Choose to display the normal curve (under Element Properties) and title your charts. Copythese plots into your Word document.3. Now create probability-probability (p-p) plots for each variable. This output will give you additionalinformation. Read over the Case Processing Summary. Notice that there is missing data for Days 2 andDay 3. Copy only the Normal p-p Plots into your Word document (you do not need to copy thebeginning output nor the Detrended Normal p-p Plots).4. Examining the histograms and p-p plots, describe the dataset with particular attention toward theassumption of normality. For each day, do you think the responses are reasonably normally distributed?(Just give your impression of the data.) Why or whynot?5.Using the same dataset and the Frequency command, calculate the standard descriptive measures(mean, median, mode, standard deviation, variance and range) as well as kurtosis and skew for all threehygiene variables. Paste your output into your Word document (you do not need to paste the FrequencyTable). What does the output tell you? You will need to comment on: sample size, measures of centraltendency and dispersion and well as kurtosis and skewness. You will need to either calculate z scoresfor skewness and kurtosis or use those given in the book to provide a complete answer. Bottom line:is the assumption of normality met for these three variables? Does this match your visual observationsfrom question #1?6. Using the dataset SPSSExam.sav and the Frequency command, calculate: the standard descriptivestatistics (mean, median, mode, standard deviation, variance and range) plus skew and kurtosis, andhistograms with the normal curve on the following variables: Computer, Exam, Lecture, and Numeracyfor the entire dataset. Complete the same analysis using University as a grouping variable. Paste youroutput into your Word document (you do not need to paste the Frequency Table). What do the results

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tell you with regard to whether the data is normally distributed?7. Using the dataset SPSSExam.sav, determine whether the scores on computer literacy and percentageof lectures attended (with University as a grouping variable) meet the assumption of homogeneity ofvariance (use Levene’s test). You must remember to unclick the “split file” option used above beforeconducting this test. What does the output tell you? (Be as specific as possible.)8. Describe the assumptions of normality and homogeneity of variance. When these assumptions areviolated, what are your options? Are there cases in which the assumptions may technically be violated,yet have no impact on your intended analyses? Explain.

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1.Why do we care whether the assumptions required for statistical tests are met? (Tip: You might alsowant to write your answer on a note card you paste to your computer.)Assumptions are needed to draw accurate conclusions about realitytest Different assumptions aremadeforvariousstatisticalmodelsandinorderformodelstoreflectrealityaccurately;theirassumptions need to be true.If assumptions are broken, accurate conclusions cannot be drawn aboutthe data distribution. Therefore, part of the data process involves checking to make sure that your datadoesn't fail this assumption.2. Open the data set that you corrected in Activity #1 for DownloadFestival.sav. You will use the followingvariables: Day1, Day2, and Day3 (hygiene variable for all three days). Create a simple histogram for eachvariable. Choose to display the normal curve (under Element Properties) and title your charts. Copythese plots into your Word document.

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3. Now create probability-probability (p-p) plots for each variable. This output will give you additionalinformation. Read over the Case Processing Summary. Notice that there is missing data for Days 2 andDay 3. Copy only the Normal p-p Plots into your Word document (you do not need to copy thebeginning output nor the Detrended Normal p-p Plots).
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