11) Adding a predictor to a regression model causes which of the following changes?a) SSError decreases and SSRegression increases.b) SSError increases and SSRegression decreases.c) Both SSError and SSRegression decrease.d) Both SSError and SSRegression increase.

A pharmaceutical company is testing a new drug for a rare disease. In a clinical trial, 1000 patients with the disease were randomly assigned to receive either the new drug or a placebo. After one year, it was found that 60% of the patients who received the new drug experienced improvement, compared to only 40% of those who received the placebo. Is the difference in improvement rates statistically significant? Provide your rationale.

4. A study is conducted in patients with HIV. The primary outcome is CD4 cell count, which is a measure of the stage of the disease. Lower CD4 counts are associated with more advanced disease. The investigators are interested in the association between vitamin and mineral supplements and CD4 count. A multiple regression analysis is performed relating CD4 count to use of supplements (coded as 1 = yes, 0 = no) and to duration of HIV, in years (i.e., the number of years between the diagnosis of HIV and the study date). For the analysis,  = CD4 count.   = 501.41 + 12.67 Supplements – 30.23 Duration of HIV What is the expected CD4 count for a patient not taking supplements who has had HIV for 5 years?   A) 350.26 B) 501.41 C) 30.23 D) 5

Which of the following statements about a least-squares regression analysis is true?I. A point with a large residual is an outlier.II. A point with high leverage has a -value that is not consistent with the other -values in the set.III. The removal of an influential point from a data set could change the value of the correlation coefficient.

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A study of elementary school children, ages 6 to 11, finds a high positive correlation between shoe size x and score y on a test of reading comprehension. The observed correlation is most likely due to:     the effect of a lurking variable, such as age or years of reading experience.     a mistake, because the correlation must be negative.     cause and effect (larger shoe size causes higher reading comprehension).     reverse cause and effect (higher reading comprehension causes larger shoe size).

a ift = The table below gives the age and bone density for five randomly selected women. Using this data, consider the equation of the regression line, bo + b₁x, for predicting a woman's bone density based on her age. Keep in mind, the correlation coefficient may or may not be statistically significant for the data given. Remember, In practice, it would not be appropriate to use the regression line to make a prediction if the correlation coefficient is not statistically significant. tab ** Answer How to enter your answer (opens in new window) Step 2 of 6: Find the estimated y-Intercept. Round your answer to three decimal places. esc 1945 ! 1 q alt a Z ebook x360 ng from any angle. @ 2 W S →>> X # 3 e d C $ 4 C r f Age Bone Density 359 % 5 V t g 36 51 63 66 70 357 328 314 310 Oll A 6 b y hp h & 7 O n u j * 8 N O i m ( 9 k O 100- 4 Tables ctrl { [ Keypad Keyboard Shortcuts Previous step answers Submit Answer D + = 11 : 90 ; ? Copy Data O SEAR Dec 2 Table ] USE YOUR SMARTPHONE FOR…

A team of epidemiologists at the Mayo Clinic wanted to find whether there is an association between obesity and cardiovascular disease (CVD). They conducted a prospective cohort study following obese and non-obese individuals who were free of CVD at the beginning of study for five years. The investigators were also interested in assessing age as a potential confounder, effect modifier, or both. Use the data below to answer the accompanying questions.     CVD No CVD Total Obese 10 90 100 Not Obese 35 465 500 Total 45 555 600       CVD No CVD Total Obese 36 164 200 Not Obese 25 175 200 Total 61 339 400   1. Compute the appropriate measure of association for those who were less than age 50.  2. Compute the appropriate measure of association for those who were older or equal to age 50.  3. Compute the crude measure of association?  4. List three attributes that age must satisfy before it could…