Stats Chapter 4 Quiz
A news release for a diet product company reports: "We have good news for the 65 million Americans currently on a diet." Its study showed that people who lose weight can keep it off. The sample consisted of twenty graduated on the company's program who endorsed it in commercials. The results of the study are probably...
Biased, overstating the effectiveness of the diet.
A marine biologist wants to estimate the mean size of the barnacle Semibalanus balnoides on a stretch of rocky shoreline. To do so, he randomly selected twenty ten by ten square inch plots and measured the size of every barnacle in each selected plot. This is an example of...
Cluster Sampling
If changes in a response variable might be due to the effects of the explanatory variable as well as the effects of a third variable, and we cannot distinguish between these effects, the explanatory variable and the third variable are said to be...
Confounded
To assess the opinion of students at the University of Minnesota about campus snow removal, a reporter for the student newspaper interviews the first 12 students he meets who are willing to express their opinion. The method of sampling used is...
Convenience Sampling
Mrs. Weber wants to know the true average of all players currently on the active roster in the National Football League (NFL). She selects a random sample of 40 NFL players and determines each players age from information avaliable information on the internet. Identify the population and the sample...
The population in the study Mrs. Weber is doing is every player that is currently involved in the NFL while the sample is the 40 NFL players that are selected randomly.
A television station is interested in predicting whether voters in its viewing area are in favor of offshore drilling. It asks its viewers to phone in and indicate whether they support/ are in favor of or are opposed to this practice. Of the 2241 viewers who phones in, 1574 (70%) were opposed to offshore drilling. The viewers who phoned can be best described as...
A Voluntary Response Sample
A simple random sample of size n is defined to be...
A sample chosen in such a way that every set of n units in the population has an equal chance to be the sample that is actually selected.
A simple random sample is...
A sample that gives every possible sample of the same size from the same population the same chance to be selected.
One hundred volunteers who suffer from severe depression are available for a study. Fifty are selected at random and are given a new drug that is thought to be particularly effective in treating severe depression. The other fifty are given an existing drug for treating severe depression. A psychiatrist evaluated the symptoms of all volunteers after four weeks in order to determine if there has been substantial improvement in the severity of the depression. The study would be double blind if...
All Of The Above
The essential difference between an experiment and an observational study is that...
An experiment imposes treatments on the subjects, but an observational study does not.
Does caffeine improve exam performance? Suppose all students in the 8:30 section of a course are given a "treatment" (two cups of coffee) and all students in the 9:30 section are not permitted to have any caffeine before the mid-term exam. The response variable in this study is...
Exam Performance
We divide the class into two groups: first year students and others. We then take random samples from each group. This is an example of...
Stratified Random Sampling