Exam 2: Collecting Data Sensibly

Two factors are extraneous if their effects on the response variable cannot be distinguished from one another.

The method of control wherein an extraneous variable is held constant is called blocking.

A treatment is any particular combination of values for the explanatory variables.

As long as the sample size is small relative to the population, there is little practical difference between sampling with replacement and sampling without replacement.

In competitive sports, video recorders have been used more frequently in recent years. The idea behind the recorder is that coaches can replay training sessions for more effective feedback to the athlete.Some people believe video recording may make the athletes more nervous and actually decrease their performance.You have been asked to design an experiment to address this issue for competitive high school tennis players. You have decided to use the accuracy of tennis serves as your response variable, and the number of successful serves out of 100 as your performance measure.The subjects for your experiment are 60 high school male competitive tennis players of varying ability who have volunteered for the experiment.

Random assignment of volunteers should result in comparable experimental groups.

Replicating in an experiment means that the number of subjects is greater than 1.

The following paragraph describes an actual study.After reading the description, determine whether the study is an observational study or an experiment.Justify your answer with specific references to the information in the study. "We compared paired daytime and night counts of wild brook trout, brown trout, and rainbow trout made by the same snorkelers in five streams during August 1994.Overall, we counted 109 trout in the daytime and 333 trout at night.We speculate that trout counted at night were present during the daytime but were hidden from view.Biologists should consider that trout behavior and susceptibility to being seen might vary a great deal between daytime and night, even during summer.In some streams, the majority of trout may not be seen during the daytime."