Exam 19: Nonparametric Statistics

Movie Scripts In general,before a producer agrees to make a movie,each script is thoroughly reviewed by movie editors.Suppose that the Big-Screen Film Company has recently received two scripts for new movies.To help them decide which one to produce,both are sent to 30 editors who rate the scripts to judge which one is better.Suppose that 10 editors rate script 1 better and 20 rate script 2 better. -{Movie Scripts Narrative} Can Big-Screen conclude at the 5% significance level that script 2 is more highly rated than script 1?

To determine whether a relationship exists between two variables,the hypotheses to be tested are H₀: r_s = 0 vs.H₁: r_s $\neq$ 0.

Coffee A supermarket chain has its own house brand of coffee.The general manager claims that their coffee is better than the coffee sold by a well-known Coffee Shop chain.To test the claim 40 individuals are randomly selected to participate in the following experiment.Each respondent is given the two brands of coffee to taste (without any identification)and asked to judge which one is better.Suppose that 25 people judge the Coffee Shop chain brand better,four say that the brands taste the same,and the rest claim that the supermarket brand is better. -{Coffee Narrative} What is the p-value of the test in the previous question?

When data are ordinal and you want to analyze matched pairs differences,you use the ____________________ test.

The procedure for the Wilcoxon rank sum test requires that we rank each group separately rather than together.

Because of the rising costs of construction accidents many construction firms have instituted safety courses.Employees are encouraged to take these courses designed to heighten safety awareness.A company is trying to decide which one of two courses to institute.To help make a decision,eight employees take course 1 and another eight take course 2.Each employee writes a test,which is marked,out of a possible 25.The results are shown below.Does this data provide sufficient evidence at the 5% level of significance to conclude that the marks from course 2 are higher than those of course 1? Assume that the scores are not normally distributed. Safaty Tast scores Course 1 Caurse 2 14 20 21 18 17 22 14 15 17 23 19 21 20 19 16 15

The ____________________ correlation coefficient is used to look for a linear relationship between x and y when both variables are interval and have normal distributions.

When the data are interval,how does the Wilcoxon signed rank sum test compare to the sign test?

The sign test statistic is approximately normally distributed whenever the sample sizes are larger than:

Airlines Ranking Ten business people who fly frequently from Las Vegas to Miami were asked to rank four airlines in terms of the quality of service.The people assigned scores using a 5-point Likert scale where: 1 = bad,2 = poor,3 = average,4 = good,and 5 = excellent.The results are shown below: Airline Person A B C D 1 1 3 5 2 2 5 4 2 1 3 2 5 3 2 4 4 2 4 1 5 3 3 1 5 6 4 4 5 3 7 3 4 1 4 8 2 5 2 1 9 5 3 4 2 10 5 5 4 3 -{Airlines Ranking Narrative} Using the appropriate statistical table,what statement can be made about the p-value for the test in the previous question? Explain how to use the p-value for testing the hypotheses.

If both variables have a normal distribution,you should use the Spearman rank correlation coefficient to look for relationships,rather than the Pearson correlation coefficient.