Dr. Jones conducted a study examining the relationship between the amount of sugar in a child’s diet and the activity level of the child. A sample of 30 four-year-old children from a local preschool was used in the study. Sugar consumption was measured by interviewing the parents about each child’s diet. Based on the result of the interview, each child was then placed into one of two groups: high sugar consumption and low sugar consumption. Activity level was measured by observing the children during a regular preschool afternoon. Finally, Dr. Jones compared the activity level for the high-sugar group with the activity level for the low-sugar group. Explain why Dr. Jones’ study is not an example of the experimental research strategy and provide way that it can be tested experimentally.

A researcher conducts an independent-measures study to examine how the brain chemical serotonin is related to aggression.  One sample of rats serves as a control group and receives a placebo that does not affect normal levels of serotonin.  A second sample of rats, low serotonin group, receives a drug that lowers brain levels of serotonin.  Then, the researcher tests the animals by recording the number of aggressive responses each of the rats display.  See the data below. Is there a significant difference between the control group and the low serotonin group regarding the number of aggressive responses?                                                Control         Low Serotonin                                                    n = 10                 n = 15                                                M = 14               M = 19                                                SS = 180.5         SS = 130 Perform a hypothesis test using independent-measures t-test. Use a two-tailed…

Researchers want to estimate the percentage of people who thought drinking and driving was a serious problem. Reserchers waited outside a bar to question people. They usually find 11%of bar patrons believe drinking and driving is a serious problem. a. identify the populatin of interest b. identify the sample c. identify the population parameter of interest d. identifywho if anyone was left out of the study

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?