Experimental Design and Sampling Method Review

The teacher samples her class by selecting all students sitting at group 1 and group 5 in her classroom.  This sampling technique is called?

• SRS

• Stratified

• Systematic

• Cluster

210 college students were randomly assigned to play either a violent or nonviolent video game.  A short time later, the students were presented with the opportunity to trivially harm another person and results comparing the two groups were recorded.
Is this study OBSERVATIONAL or EXPERIMENTAL? 

• Observational

• Experimental

At a middle school, the 7th graders will conduct a survey for where to go on a field trip. Which method will result in the least biased decision?

• to randomly ask 8th grade students who went on a field trip last year

• to randomly choose some 7th grade students to select a location

• to ask all 7th grade teachers and administrators for a location

• to ask the student council to choose a location

Which sampling method reduces variability?

• SRS

• Stratified

• Cluster

• Systematic

A reading specialist in a large public school system believes that the more time students spend reading, the better they will do in school. She plans a middle school experiment in which an SRS of 30 eighth graders will be assigned four extra hours of reading per week, and SRS of 30 seventh graders will be assigned two extra hours or reading per week, and an SRS of 30 sixth graders with no extra assigned reading will be a control group. After one school year, the mean GPAs from each group will be compared. Is this a good experimental design?

• Yes

• No, because while this design may point out an association between reading and GPA, it cannot establish a cause-and-effect relationship.

• No, because without blinding, there is a strong chance of a placebo effect.

• No, because any conclusion would be flawed because of blocking bias.

• No, because grade level is a lurking variable which may well be confounded with the variables under consideration.

Interview every 10th student who enters the school in the morning.

• simple random

• voluntary response

• systematic

• convenience

The president of a college randomly selects 2 students from each department to serve on a student advisory board.

• Convenience

• Systematic

• Stratified

• Simple Random

Farmer Joe separates his apple tree farm into 10 regions.  He counts the number of apples produced in just one of the regions and uses that estimate to predict the number of apples produced on the whole farm.  This is _______ sampling.

• Simple

• Cluster

• Stratified

• Systematic

To study the amount of time students spend doing homework each day, use a random number generator to select 25 students from the student enrollment database to survey.

• Convenience Sample

• Simple Random Sample

• Stratified Random Sample

• Interval Sample

To determine whether sugar affects an athlete’s performance at practice, Coach Barron gave half the team doughnuts for breakfast and the other half whole grain cereal. He compared the two groups in terms of endurance and energy. This is an example of:

• Observational Study

• Experimental Study