A new headache remedy was given to a group of 25 subjects who had headaches. Four hours after taking the new remedy, 20 of the subjects reported that their headaches had disappeared
Nothing, because there is no control group for comparison
We wish to draw a sample of 5 without replacement from a population of 50 households. Suppose the households are numbered 01, 02,.....,50, and suppose that the relevant line of the random number table is
Households 11 36 23 08 42
A maple sugar manufacturer wants to estimate the average trunk diameter of sugar maples trees in a large forest. There are too many trees to list them all and take an SRS, so he divides the forest into several hundred 10 meter by 10 meter plots, selects 2
Cluster sample
A researcher for a consumer products company is field testing a new formula for laundry detergent. He has contracted with 60 families, each w 2 children, who have agreed to test the product. He randomly assigns 30 families to the group that will use the n
Randomization is a good way to create 2 groups of 30 families that are as similar as possible, so that comparisons can be made between the 2 groups
To test the effect of music on productivity, a group of assembly line workers are given portable mp3 players to play whatever music they choose while working for one month. For another month, they work without music. The order of the 2 treatments for each
A matched pairs experiment
A survey was done in the town of Mechanicsville to estimate the proportion of cars that are red and made by companies based in japan. A random sample of 25 cars from a student parking lot at Lee- Davis High School was taken. Which of the following stateme
The results will be the same regardless of the time of day that the sample is taken
A nutritionists wants to study the effect of storage time (6, 12, and 18 months0 on the amount of vitamin C present in freeze dried fruit when stored for these lengths of time. Vitamin C is measured in milligrams per 100 milligrams of fruit. Six fruit pac
A specific storage time, a fruit pack, and amount of vitamin C
A researcher observes that, on average, the number of divorces in cities with Major League Baseball teams is larger than in cities without Major League Baseball teams. The most plausible explanation for this observed association is that the...
Association is due to the presence of a lurking variable ( major league teams tend to be in large cities with more people, hence a greater number of divorces)