A doctor released the results of clinical trials for a vaccine to prevent a particular disease. In these clinical trials, 400,000 children were randomly divided in two groups. The subjects in group 1 (the experimental group) were given the vaccine, while the subjects in group 2 (the control group) were given the 200,000 children in the control group, 109 developed the disease. Complete parts (a) through (f) below. placebo. Of the 200,000 children in the experimental group, 41 developed the disease. Of (a) What type of experimental design is this? O Completely randomized design O Matched-pairs design O Randomized block design O Case-control (b) What is the response variable? OA. Whether the subject contracted the disease or not OB. Whether the subject was in group 1 or group 2 OC. Whether the vaccine prevented the disease or not OD. The amount of the vaccine received (c) What are the treatments? OA. The vaccine or placebo OB. Group 1 or group 2 OC. The amount of the placebo received

A pharmaceutical company is testing the effectiveness of its vaccine across two different age brackets. They take a sample and split the participants up into two separate groups. Group A consists of 44 people who are between ages 13 and 18. Group B consists of 58 people between ages 19 and 26. After being administered the vaccine, it was found that 37 people from group A were immune to the virus and 42 people from group B were immune. (this is the same situation from the previous daily) Why do we use the 'pooled proportion' instead of the null hypothesis in the denominator of the test statistic? At a 10% significance level, is there reason to believe there is a difference in vaccine efficacy between Group A and Group B?  explain each step

In a large clinical​ trial, 394,108 children were randomly assigned to two groups. The treatment group consisted of 198,537 children given a vaccine for a certain​ disease, and 30 of those children developed the disease. The other 195,571 children were given a​ placebo, and 105 of those children developed the disease. Consider the vaccine treatment group to be the first sample. Complete parts​ (a) through​ (d) below.

A study was conducted to determine whether big-city and small-town dwellers differed in their helpfulness to strangers. In this study, the investigators rang the doorbells of strangers living in a large City or small towns in the vicinity. They explained they had misplaced the address of a friend living in the neighbourhood and asked to use the phone. The following data show the number of individuals who admitted or did not admit the strangers (the investigators) into their homes: Helpfulness to strangers   Admitted strangers into their home  Didnot admit strangers into their home  Big city dwellers 60 90 Small town dwellers 70 30 State the dependent and independent variable  Is this a directional or non directional

One year at a university, the algebra course director decided to experiment with a new teaching method that might reduce variability in final-exam scores by eliminating lower scores. The director randomly divided the algebra students who were registered for class at 9:40 A.M. into two groups. One of the groups, called the control group, was taught the usual algebra course; the other group, called the experimental group, was taught by the new teaching method. Both classes covered the same material, took the same unit quizzes, and took the same final exam at the same time. The final-exam scores (out of 40 possible) for the two groups are shown in the accompanying table. Find a 99% confidence interval for the ratio of the population standard deviations of final-exam scores for students taught by the conventional method and for students taught by the new method. Assume that both populations are normally distributed. (Note: s₁ = 6.613, $₂ = 5.762, and for df = (19,40), F0.005 = 2.63.) Click…

A basketball coach is interested in determining if shooting free throws underhand is better than shooting them using the overhead method. He has four high school teams (two boys' teams and two girls' teams, with 13 players on each team) available to take part in an experiment. He believes that the difference in shooting percentages will vary more for boys than for girls. He randomly chooses and instructs half of the boys to continue shooting free throws overhead and the rest of the boys to shoot underhand. He does the same for the girls. At the end of a six-game summer league, he compares the shooting percentages for the overhead shooting boys to the underhand shooting boys and the overhead shooting girls to the underhand shooting girls. (a) What is the advantage of using a block design for this study? O Blocking by gender will reduce the variation in the response variable by creating homogeneous groups and determining the effect of the new shooting style on the response (percentage of…

A psychologist has developed a mental alertness test. She wishes to study the effects (if any) of type of food consumed on mental alertness. Twenty-one volunteers were randomly divided into two groups. Both groups were told to eat the amount they usually eat for lunch at noon. At 2:00 P.M., all subjects were given the alertness test. Group A had a low-fat lunch with no red meat, lots of vegetables, carbohydrates, and fiber. Group B had a high-fat lunch with red meat, vegetable oils, and low fiber. The only drink for both groups was water. The test scores are shown below. Group A 75 82 96 54 78 59 67 53 97 85 66   Group B 70 80 79 60 62 71 52 69 64 88 51 74 Use a 10% level of significance to test the claim that there is no difference in mental alertness distributions based on type of lunch. (a) What is the level of significance?State the null and alternate hypotheses. Ho: Distributions are different. H1: Distributions are the same.Ho: Distributions are the same. H1:…

A researcher conducted a study to determine whether a new type of phys- ical therapy would help people recovering from knee injuries. The study included 10 patients, and 5 physical therapists. The researcher decided to conduct the experiment using a matched pairs design, as follows: Two patients were (randomly) assigned to each physical therapist. Then, one of the two patients was randomly chosen to receive the new treatment, while the other received the old treatment. After one week, the researcher measured each patient’s improvement in range of motion (ROM), in degrees (◦). (a) Describe the benefit of conducting a matched pairs experiment in this way. (b) The table/image attached to this question shows the data obtained from this experiment: By hand, carry out a t-test to see if the mean difference in ROM improvements between the two treatments (New minus Old) is greater than zero.