Provide R code, output and written interpretation for parts a) to d) of this question. Provide only output that is directly relevant to address each section.
Test for multivariate normality (MVN) by:
a). Provide output from the structure function and describe the structure of the ‘film_2023.txt’ data. b). Produce and interpret univariate QQ plots, histograms and univariate ShapiroWilks tests of normality for each of the four film thickness variables. What is the default univariate test produced by the mvn function? c). Produce and interpret perspective and contour plots for the TopRight and TopLeft film t hickness v ariables. W hat is a n i nherent p roblem w ith using these plots to assess MVN? d). Do the analysis necessary to provide the results of the Mardia, Henze-Zirkler and Royston tests of MVN based on all four film thickness v ariables. Include in your i nterpretation:
• The Chi-Square QQ plot and interpretation. • Describe how the QQ plot is constructed and its relationship to the univariate normal QQ plots. • Output and interpretation for the 3 tests. • What is a key limitation of these MVN statistical tests?
e). If your data does not meet MVN, why might you need to consider the ratio of cases to variables? (This question does not necessarily relate specifically to this particular data set)