Question

In what follows use any of the following tests: Regression, multiple regression, one-sided t-test or two-sided t-test. All conclusions should be based on 5% P-value threshold. Choose the best fitting answer. Open Brains data and create two columns: first containing male head circumference and second containing female head circumference. 13. Task A: Perform two-sided t-test comparing the two columns (male and female head circumference). What is the P-value? a. 0.000906932 b. 0.001813863 c. 0.300805939 d. 0.000303496 14. Task B: Perform regression where X-axis is the male head circumference and Y-axis is female head circumference. What is the P-value related to the slope? a. 0.000906932 b. 0.001813863 c. 0.270482 d. 0.000303496 15. Do these tests make sense? a. Only t-test makes sense in this setting. b. Only regression makes sense in this setting. c. Both tests make sense in this setting. d. Neither of the two tests make sense.

https://www.limes.one/Content/DataFiles/Brains.txt

Answer 1

13. Task A: The R command to perform the t test is as shown below: > MaleHC<-c(57.2,57.2, 57.2,57.2, 58.5, 57.2, 57.2, 55.8, 56.5, 59.2) > FemaleHC<-c(54.7, 53, 57.8, 56.6, 53.1,54.2, 52.9, 56.9, 55.3, 54.8) > t.test (MaleHC, FemaleHC) Welch Two Sample t-test data: MaleHC and FemaleHC t = 3.8415, df = 13.925, p-value = 0.001814 alternative hypothesis: true difference in means is not equal to 0 95 percent confidence interval: 1.054935 3.725065 sample estimates: mean of x mean of y 57.32 54.93 Therefore, the P-value is b. 0.001813863

14. Task B: The R command to perform regression is as shown below: > M<-1m (FemaleHC-MaleHC) > summary (M) Call: lm (formula = FemaleHC - MaleHC) Residuals: 10 Median -2.1149 -0.9502 -0.2625 30 1.1236 Max 2.7851 Coefficients: Estimate Std. Error t value Pr (tl) (Intercept) 95.4755 34.2553 2.787 0.0237 * MaleHC -0.7074 0.5975 -1.184 0.2705 Signif. codes: 01***' 0.001 ***1 0.01 1*' 0.05 . 0. 1 Residual standard error: 1.69 on 8 degrees of freedom Multiple R-squared: 0.1491, Adjusted R-squared: 0.04269 F-statistic: 1.401 on 1 and 8 DF, p-value: 0.2705 Therefore, the P-value is 0.270482 15. a. Only t-test makes sense in this setting. Good luck with your studies!!!