Question

TEST 1: ANSWERS INTS EACH). This section takes around 5 minutes. Name Spring 2019 8) A researcher wants to determine whether female teachers give higher or lower grades, on average, then male teachers. She picks a random sample by picking a random sample of schools, in the schools picked, picking a random sample of departments, and in the departments picked, picking a random sample of teachers. What kind of sampling was performed? d) voluntary response e) cluster b) stratified Random 4) 234 students out of 400 in the population of ABC High School ninth graders belong to clubs. What is proportion of club members in the population? .234-23.4% T-400-234-lif 400 400 ( d) a) c)z-234400-0.059 b)s-234/400 . 0.59 Which is NOT one of the advantages of stratified samples? a) A sample is picked by randomly sampling each group or "stratum" enabling proportional representation b) This type of sampling enables researcher to compare a small sub-population to a large sub-population e) Such random samples save time and money, compared to other types of random and systematic samples d) This sample allows researchers to focus on effects of important explanatory variables in different strata For items # 11-15 "The Math Skills Study" dicirious): A study to measure the effectiveness of an Arithmetic Skills Improvement (ASD) Program for elementary school children in Minnesota is conducted as follows: A sample of n 568 first grade children across MN is collected and permission is obtained from the parents. The children take a pre-test. Then h of the children are randomly assigned to the ASI program, and the rest take the regular İtgrade mathematcs. At the end of the year, all the children take a post-test, and the results of the ASI and the regular 11) How would you classify the Math Skills Study described? a) a placebo-controlled study b) a double-blind study e) an experiment d) an observational study 12) How would you classify the regular Program group of children? a) the biased group b) the control group e) the treatment group dthe lurking variable group 13) What is the response variable in this study? a) the ASI or regular math program c) the 568 children in the study b) the score(s) on the arithmetic post-test d) the 95% Confidence Interval for 14) What would be the Ha for mean Arithmetic Test scores in this study? 15) What would be the sources of uncertainty in this study? a) Children were not genetically profiled and there was no placebo administered b) The children were not allowed to choose the program, and bias could result. c) The lurking variables, such as diet, heredity, mathematical attitude and ability d) The children are from Minnesota, but ANSI could benefit Hawaiians as well Spring 2019 Name IV) ORGANIZING and Assessing DATA: graphs and simple calculations 16) In density distributions (for example, the Normal), the Area under the curve is a) l or 100% Probability b) whatever we want e) usually unknown d) varies depending on sample size 17) We visualized data by using different plots. Which of the statements below is a) scatterplots display 2 variables at a time, for each subject b) some histograms can be approximated by a Normal curve c) boxplot displays statistics for many variables at a time d) except for scatterplots, all plots above display 1 variable FALSE? 18) What are the 2 #s that completely describe the Normal distribution? a) range and median b) mean and median (mean and standard deviation d) mean and proportion 19) The 5 point summary of the data that is used in a boxplot consists of a) low, mean, median, proportion, sid, deviation c) low, 25th-stile, median, 75th%tile, high b) low, 25th%tile, mean, 75th%tile, high d) mean, median, proportion, std. deviation, range 1, 3, 5, 20, 14 20) The ordered stemplot of the mumber of rainy dapys 12, 6.5, 12,s,3,0, d) oLj0133 OH) 5568 1U224 IH] 2L]0 c) OL) 313 0H) 6585 IL] 24 IH) 2110 b) OL] 3013 0H] 6585 IL]224 IH] 21) The graph in 20a) could be improved by to group data (more bars) b) making bars from-03-4.5, 45-9.5, etc. for discrete d) using a Normal distribution and indicating the mean c) performing an experiment and using a placebo 22) The correct boxplot of the data in 20) is: 23) The purpose of a scatterplot is to a) visually assess the size of the residuals for a model for 2 variables b) see whether a linear relationship exists between 2 variables c) to determine the appropriateness of a linear model visually d) may be any or all of the purposes above, depending on the data 24) The purpose of calculating the sample statistics for example, the sample proportion a) to summarize or "put together" sample data e) neither a) nor b) b) to estimate population parameters d) could be either a) or b) or both V) ANALYSIS OF DATA For items # 25-27 use the table below: 9th grade 10h grade Right-handed 234166 Left (or other) 46 | 54 25) Calculate Probability that a-randomly picked person is a left-handed 9h grader 9) 0.390 b) -0.234 0384 0243 26) Calculate Probability that a randomly picked 9* grader is a left-handed 20.390 d) 0.243 b)-0.234 0.384 d) 0.243 27) Calculate Probability that a randomly picked person is a right-handed, or 10th grader b)0.243 a) 0.757 c)0.277 d) 1.033 28) Calculate Probability that two randomly picked persons are left-handed a) 0.666 b) 0.333 )0.999 d) 0.111 29) Which values of the correlation coefficient r are indicative of "very high correlation" between the variables x and y? a)lor-100% b)-02,-01, 0, 0.1, 0.2 c)-I,-09,-09, 1 d) 0, 0.1... 0.9,1 30) Negative correlation between the numeric variables x and y indicates that a) as x increases, y decreases c) x does not cause y b) the regression line is weak d) there is a weak corelation e correlation between the variables the average # of cigarettes smoked per day and 31) Th death rate (deaths per million) because of lung cancer is probably a) positive b) negative c) needs a z2 test d) no correlation 32) Correlation(s) indicate(s) that that all points of a scatterplot lie on the regression line? d)slope > 0 a) r 0 b)r=-1 or 1 e) r-1

Answer 1

8) b. Stratified sampling ---- Since all the schools are stratified into various stratas. Out of those certain are randomly sampled from which again departments are randomly sampled and in the end teachers are randomly sampled.

9(4)) b. $\pi$ = 234/400 = 0.59 -- Number of students out of 400 that are club members/ Total number of students.

10(5)) c. Such random samples save time and money, compared to other types of random and systematic samples. -- Simple random samples and systematic samples are much more cost and time effective compared to stratified sampling.

11) a. a placebo-controlled study -- since one part of the random sample was subjected to ASI program and the other part was subjected to take regular 1^st grade mathematics.

According to HOMEWORKLIB POLICY we are instructed to answer first 4 questions.