Planning a Study

Consider an experiment to investigate the effectiveness of different insecticides in controlling pests and their effects on subsequent yield. What is the best reason for randomly assigning treatment levels (spraying or not spraying) to the experimental units (farms)?

• Randomization makes the experiment easier to conduct since we can apply the insecticide in any pattern rather than in a systematic fashion.
• Randomization will tend to average out all other uncontrolled factors such as soil fertility so that they are not confounded with the treatment effects.
• Randomization makes the analysis easier since the data can be collected and entered into the computer in any order.
• Randomization is required by statistical consultants before they will help you analyze the experiment.

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CCSS.HSS.IC.B.3

CCSS.HSS.IC.B.5

In order to perform an experiment using 60 members of a gym, I first divide the list of members into men and women because I feel that the results will be different based on gender. I then randomly choose 30 men and 30 women. I assign half of the men to the treatment group and half to the control group. I repeat this procedure with the women. This is an example of a:

• randomized comparative design
• blocking design
• matched pairs design
• double blind simple random sample

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CCSS.HSS.IC.B.3

CCSS.HSS.IC.B.5

A recent study showed that tea drinkers have lower stress levels than coffee drinkers. Tea drinkers are known to have a higher proportion of yoga practitioners than coffee drinkers, and they exercise on average two hours per week more than their coffee-drinking counterparts. What is the term used to describe these additional factors that might have an effect on the stress levels of tea drinkers?

• cause and effect variables
• confounding variables
• sampling variables
• unfounded variables

Experimental Design (3)
In an experiment, the control group should receive

• A) Treatment opposite the experimental group.
• B) The same treatment as the experimental group without knowing they are receiving the treatment.
• C) A procedure identical to the experimental group except for recieving the treatment under examination.
• D) A procedure identical to the experimental group except for a random decision on receiving the treatment under examination.

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CCSS.HSS.IC.B.3

Experimental Design (5)
In a study of the effect of music on worker productivity, employees were told that a different genre of background music would be played each day and the corresponding production outputs noted.  Every change in music resulted in an increase in production.  This is an example of

• A) the effect of a treatment unit.
• B) The placebo effect.
• C) sampling error.
• D) voluntary response bias

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CCSS.HSS.IC.B.3

Sample Methods (9)
What is a sample?

• A) A measurable characteristic of a population.
• B) A set of individuals having a characteristic in common
• C) A value calculated from raw data.
• D) A subset of a population

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CCSS.7.SP.A.1

CCSS.HSS.IC.A.1

If you were testing how well different dish soap cleaned grease, the independent (experimental) variable would be the:

• Dishes
• Water
• Dish Soap
• Types of Grease

Principal Rusk picks 75 students at a recent varsity football game to be used for the sample.  This is what type of sampling design?

• SRS
• Stratified
• Convenience
• Voluntary Response

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CCSS.HSS.IC.B.3

An SRS of 25 students is taken from each grade to form the sample.  This is what type of sampling design?

• Cluster
• SRS
• Stratified
• Multistage

Tags

CCSS.HSS.IC.A.1

CCSS.HSS.IC.B.3

The question about the theme for prom is posed during the morning announcements.  Students are asked to go to the main office between classes to give their answer to the question.  This is what type of sampling design? 

• Cluster
• Convenience
• Voluntary Response
• SRS