Two hundred people were randomly selected from a list of all people living in Minneapolis who receive Social Security. Each person in the sample was asked whether or not they took calcium supplements. These people were followed for 5 years, and whether or not they had a heart attack during the 5-year period was noted. The researchers found that the proportion of heart attack victims in the group taking calcium supplements was significantly higher than the proportion of heart attack victims in the group not taking calcium supplements. A)  observational study or an experiment B) Did the study use random selection from some population? (Yes or No) C) Did the study use random assignment to the experimental groups? (Yes or No) D) Based on the description of the study, is it reasonable to conclude that taking calcium supplements if the cause of the increased risk of a heart attack? (Yes or No)

This obstetrician also wanted to determine the impact that three experimental diets had on the birth weights of pregnant mothers. She was also interested if age had an impact on birth weights. She randomly selected 27 pregnant mothers in the first trimester of whom 9 were 20 to 29 years old, 9 were 30 to 39 years old, and 9 were 40 or older. For each age group, she randomly assigned the mothers to one of three diets. After delivery, she measured the birth weight (in grams) of the babies and obtained the data a) What is the blocking variable?

A recent study investigated whether cell phone users experience separation anxiety when they cannot access their phones. Because blood pressure increases with anxiety, the researchers used systolic blood pressure as an operational measure of anxiety. The experiment involved a random sample of cell phone users that were divided into two groups at random. One group of participants completed a survey while their phones were locked in a cabinet in a separate room and the other group of participants completed the same survey while their phones were nearby. (The survey questions were unrelated to cell phone use.) At the end of the survey, theresearchers measured each participant's systolic blood pressure. The same experiment was conducted in Montreal, Toronto, Vancouver, and St. Zotique. The blood pressure data for all participants needed are below. Use these data to answer the following question: comoute the estimated standard error of d for the data collected in toronto. Please answer to 5…

An educational psychologist is interested in whether using a child’s own name in a story affected attention span while reading. Six children were randomly assigned to read a story under ordinary conditions (using common and generic names). Five other children read versions of the same story, but with each child’s ownname substituted for one of the children in the story. The researcher measured the amount of time (in minutes) each child spent reading the story. The results are shown in the following table. Does including the child’s namemake any difference in attention span?   Test the hypothesis at an alpha set to .05, following these steps: a) write the null and alternative hypotheses; b) determine the critical value(s); c) draw the comparison distribution with rejection region(s) shaded; d)use the correct formula to compute the test statistic; e) state the statistical decision; f) state a brief conclusion.

A doctor wanted to study the effect of four different treatments on mental health. A group of 100 adults experiencing depression volunteered for the study. The doctor randomly assigned one-fourth of them to each of four groups. Group 1 followed a specific exercise plan, group 2 followed a specific diet plan, group 3 followed an exercise and diet plan, and group 4 did not follow any plan. After 4 weeks, the doctor contacted each participant and asked them if they felt any better. The results are displayed in the table.    The doctor would like to know if these data provide convincing evidence that the distribution of responses differs across the treatment groups in the population of all patients like these. The random condition is met. The 10% condition is not needed because random sampling did not take place. This table of expected counts shows that all expected counts are at least 5.   What is the value of the chi-square test statistic? χ‑2 = 5.03 χ‑2 = 6.26 χ‑2 = 25.33 χ‑2 = 39.22