In an observational study, it was noticed that people that eat more chocolate tend to have better blood flow than the general population. Researchers wonder whether the improved blood flow might be caused by flavanols (a molecule found in many foods). Dark chocolate contains a high concentration of flavanols, but milk chocolate contains a much lower concentration. How could the researchers design an experiment to determine the effects of flavanol on blood flow from the different types of chocolate?

A researcher is comparing the occurrence of nausea as a side-effect in two brands of medication:  Brand A and Brand B.  For a random sample of 150 Brand A users, 66 experienced nausea as a side-effect.  For a random sample of 200 Brand B users, 118 experienced nausea as a side-effect.  Can the researcher conclude that the proportion of all Brand A users who experience nausea as a side-effect is different from the proportion of all Brand B users who experience nausea as a side-effect. For the hypothesis testing scenario above, the researcher concludes that the two proportions are different at the 0.01 significance level.  Compute the 99% confidence interval to estimate the difference.

In a recent study, authors were interested in the relationship between exposure to pesticides and incidents of ADHD. They measured levels of urinary dialkyl phosphate (DAP, a common pesticide) concentrations in a group of 1139 randomly selected U.S. children to determine ADHD diagnostic status (Yes/No). The subjects were divided into two groups based on high or low pesticide concentrations, and researchers compared the proportion with ADHD in each group. Is the proportion of children with higher exposureto pesticides more likely to develop ADHD (attention-deficit / hyperactivity disorder) than the proportion of children with low exposure to pesticides?   What are the null and alternative hypotheses?        Use the STATKEY output to answer the following:   What is the sample statistic? Use proper notation with your value.  What is the p-value?  Write a general conclusion about your hypothesis test.

A researcher surveyed 500 people. She found that the individuals who took some form of over the counter sleep aid (i.e. ZZZQuil) were able to fall asleep in a shorter period of time and stay asleep for longer periods than the individuals who did not. a) Was this study observational or experimental? Why?b) What was the explanatory variable? What was the response variable?

An experiment to determine if a migraine medication decreases a person's average number of monthly migraines is performed on 400 people who report they have several migraines a month. Researchers randomly assigned 200 people to the treatment group and 200 people to the control group. After the study, the researchers determined that 48 of the subjects in the treatment group and 28 of the subjects in the control group average fewer migraines per month. The data from the two groups are resampled 150 times, and the table shows the distribution of the differences of the proportions for the reconfigured treatment and control groups.

A researcher conducted the first four steps of an Independent ANOVA, and on step 4 he Rejected H0, concluding that the drug had some overall effect.  However, as we learned, Rejecting H0 is not really enough to call your study a “success” on ANOVA; you still need to check several more things in Step 5 and Step 6.  So, let’s say the researcher gets the following APA table on Step 5.  In which of the following cases would the drug shown on this APA table be considered a “success”?     Small Dose of Drug Medium Dose of Drug High Dose of Drug M 27.00 22.00 11.00 SD 1.00 1.73 1.00 chocies More than one of the other three options could be considered a “success” with the APA table shown If the study was investigating a memory-improving pill where the D.V. is memory score If the study was investigating a pain-reduction pill where the D.V. is pain levels If the study was investigating a depression-fighting medication where the D.V. is depression

A researcher conducted the first four steps of an Independent ANOVA, and on step 4 he Rejected H0, concluding that the drug had some overall effect.  However, as we learned, Rejecting H0 is not really enough to call your study a “success” on ANOVA; you still need to check several more things in Step 5 and Step 6.  So, let’s say the researcher gets the following APA table on Step 5.  In which of the following cases would the drug shown on this APA table be considered a “success”?     Small Dose of Drug Medium Dose of Drug High Dose of Drug M 11.00 22.00 27.00 SD 1.00 1.73 1.00     More than one of the other three options could be considered a “success” with the APA table shown If the study was investigating a depression-fighting medication where the D.V. is depression If the study was investigating a memory-improving pill where the D.V. is memory score If the study was investigating a pain-reduction pill where the D.V. is pain levels

A researcher tests reaction time of each group of 14 individuals twice once while in a very hot room and once while in a normal temperature room. What kind of t-test should be used?

Vitamin D is important for maintaining strong bones by helping the body absorb calcium from food and sup-plements. The recommended amount of vitamin D is 400 IU (international units) per day. Many people take vitamin D supplements, often at levels greatly exceeding the recommended daily amount. What is the effect of taking too much vitamin D? Researchers investigated this in a double-blind randomized clinical trial. Subjects were divided into three groups. One, consisting of 109 subjects, took 400 IU per day for three years. second group, consisting of 100 subjects, took 4,000 IU per day for three years. A third group, consisting of 102 subjects, took 10,000 IU per day for three years. The total volumetric bone mass density of the tibia (the large bone located in the lower front portion of the leg, sometimes referred to as the shinbone) was measured in order to assess the effect of the different dosages of Vitamin D.11 The degrees of freedom for the ANOVA F statistic comparing the mean…