A Negression anstyais is properly performed between two variablen. The value for r is fasand no be a.06 (negative 0.90 ) Whiefs of the following optians betat descitics the: Fietmenship kerweced thene tho variables? A) Strome relationelyep? fi) Moulerate refationbhip C) Wenak relationthip D) I tinable to detertaine 23. A researcher notices that in a sample of adults, those who take larger amounts of vitamin C have fewer illnesses. However, those who take larger amounts of vitamin C also tend to exereise more. As explanations for having fewer illnesses, the variables "amount of vitamin C taken" and "amount of exercise" are varinbles. A) skewed B) confounding C) response D) symmetric 24. Following is the output from R for a regression model predicting the murder rate "MURDERS" (per million people) from the level of unemployment ("UNEMP") Write the regression model. NOTE: You won't have space at #24 on the answer sheet, so write your answer at the bottom of the answer sheet in the space provided. Ca 77: 7m (formu 7a= murderspermi 1 unemployment) Residua7s: Min9.24151Q3.7728Median0.57953Q3.2207Max10.4221 Coefficients: (Intercept) 28.52676.81374.1870.000554 th 0 t unemployment 7.07960.96877.3098.66e07 t 0.00 25. Which of the following is the best way to establish that an observed association is the remilt of a cause-and-effect (i.e. causation) relation? A) Study the least-squares regression line. B) Use a well-designed experiment. C) Obtain the correlation coefficient. D) Examine z-scores rather than the original variables. 26. All of the following statements about scatterplots are true EXCEPT FOR: (Or to put it another way: Which of the following statements is false?) A) A scatterplor is a useful graphical tool for trying to evaluate the strength of the relationship between two quantitative variables. B) The only relationship that a scatterplot can usefully display is linear. C) An individual value that deviates significantly from the overall pattern displayed on a scatterplot is called an outlier. D) A categorical variable can be added to a scatterplot by using a different color plot or symbol for each category. 29. The graphs labeled A,B, and C, have the following possible values of the correlation coefficient:- 0.7,0.4,0.95. Assume all four graphs are made on the same seale. You may. assume that they are all linear. Which of the following graphs is most likely to have a. correlation coefficient of 0.3 ? A researeher measured the height (in feet) and volume of usable lumber (in cubie feet) of 32 . height of a tree. The results are olatted lust. volume of usable lumber ean be estimated from the 30. Select all descriptions that apply to the scatterplot. A) There is a positive association between height and volume. B) There is a negative association between height and volume. C) There is an outlier in the plot. D) Both A and C Fill in the blank. When creating a scatterplot, one should use the for the explanatory (a.k.a. independent) variable. A researeher measured the height (in feet) and volume of usable lumber (in cubie feet) of 32 . height of a tree. The results are olatted lust. volume of usable lumber ean be estimated from the 30. Select all descriptions that apply to the scatterplot. A) There is a positive association between height and volume. B) There is a negative association between height and volume. C) There is an outlier in the plot. D) Both A and C Fill in the blank. When creating a scatterplot, one should use the for the explanatory (a.k.a. independent) variable
