solved Problem 1. A permutation test for a difference of medians
Problem 1. A permutation test for a difference of medians (instead of a difference of means) can be performed using twoSamplePermutationTestLocation() in package EnvStats by including the following argument: fcn=”median”.After using library(EnvStats) and attach(mtcars), use twoSamplePermutationTestLocation() with arguments of fcn =”median” and seed = 1 to perform a permutation test for the difference of medians between the 2 data vectors wt[vs == 0] and wt[vs==1].–“seed = 1†replaces set.seed(1) for this function twoSamplePermutationTestLocation(wt[vs == 0], wt[vs==1], fcn =”median”, seed = 1 )What is the p-value of the test with seed = 1?–The seed value must be included as an argument(Answer in 0e-00 format)Problem 2. The bootstrap can be applied equally easily to test the difference of medians, a difference of standard deviations, a difference of quantiles, etc.–Unlike KS-test for the difference in CDFs, must specify a statistic to calculate a bootstrapped differenceIs the bootstrapped difference of standard deviations (sd’s) for wt significantly different from 0 (at p < 0.05) for cars with am = 0 (data vector x) and cars with am = 1 in mtcars (data vector y)? What is the bootstrapped 95% upper confidence limit for the difference in sd’s for wt between x and y using the “Basic†bootstrap?–Remember to use set.seed(1)(Answer up to 3 decimal places)Problem 3. Use kruskal.test() to test whether mothers with different numbers of physician visits in first trimester (“ftvâ€) have the same median age, in the birthwt dataset in the MASS package–library(MASS)–attach(birthwt)–Use kruskal.test()What is the p-value for the test?(Answer up to 5 decimal places)Problem 4. Chi-squared tests (c2 tests) let us compare categorical data to the predictions from a model (goodness-of-fit test), or to compare finite distributions to each other to see whether they are the same (homogeneity test) and whether they are independent (independence test).library(MASS)attach(survey)# Create contingency table for smoking vs. exercise levelstbl = table(survey$Smoke, survey$Exer) # Perform a chi-square test for independence to test whether Smoke and Exer are independent. What is the p-value of the test? (Answer up to 4 decimal places)Interpretation: Can we reject the null hypothesis that Smoke and Exer are independent at a 5% significance level?