Experiments vs Observations

What is a factor that is measured for change in an experiment?

• control

• constant

• explanatory variable

• response variable

The part of the experiment that does not contain the independent variable. Used for comparison.

• Control Group
• Experimental Group
• Results
• Data

Can pleasant aromas help a student learn better? Two researchers believed that the presence of a floral scent could improve a person’s learning ability in certain situations. They had 22 people work through a pencil-and-paper maze six times, three times while wearing a floral-scented mask and three times wearing an unscented mask. The three trials for each mask closely followed one another. Testers measured the length of time it took subjects to complete each of the six trials. They reported that, on average, subjects wearing the floral-scented mask completed the maze more quickly than those wearing the unscented mask, although the difference was not statistically significant. This study is

• a convenience sample 
• an observational study, not an experiment
• an experiment, but not a double-blind experiment 
• a double-blind experiment

The SDSU Student Union wants to know what type of events students are interested in so they decide to get a sample of undergraduate students. Which of the following would be the least useful variable to stratify by?

• major
• whether or not a student lives on or off campus
• grade level
• whether or not they drink coffee

An amateur gardener decides to change varieties of tomatoes for this year to see if the yield is improved. He puts 6 of the old type of tomato plants and 6 of the new tomato plants in his garden. The average yield for the old plants was 11.3 pounds and the average for the new plants was 14.5 pounds. This is an example of

• an experiment
• an observational study

In order to assess the effects of exercise on reducing cholesterol, a researcher sampled 50 people from a local gym who exercised regularly and 50 people from the surrounding community who did not exercise regularly. They each reported to a clinic to have their cholesterol measured. The subjects were unaware of the purpose of the study, and the technician measuring the cholesterol was not aware of whether subjects exercised regularly or not. This is

• an observational study
• an experiment

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

Tags

CCSS.HSS.IC.B.3

CCSS.HSS.IC.B.5

A study is conducted to investigate the relationship between owning pets and happiness. 100 subjects are randomly selected and data on whether or not a pet is owned and a happiness score (1‐10, 10 being extremely happy) are obtained.
Is this an OBSERVATIONAL or EXPERIMENTAL study?

• Observational
• Experimental

Tags

CCSS.HSS.IC.B.3

The three principles of experimental design are:

• Control, Randomize, Replicate

• Hypothesis, Experiment, Results

• Control, Bias, Ethics

• Design , Treatments, Comparison

If the statistical significance of an experiment is set at 15%, and the results of the experiment reveal that there is a 12% difference between treatments, what can you conclude?

• The explanatory variable does not cause a change in the response variable.

• The explanatory variable does cause a change in the response variable.

• The experimental hypothesis is true.

• The experimental hypothesis is false.