Exercise: Distinguishing Experimental Designs
This exercise is designed to give you practice at distinguishing the various true, pre-, and quasiexperiments, as well as what you can conclude from each. Using the hypothetical set of variables below,
you will create and describe two examples of studies that will fit certain designs.
As a reference, see the “Experimental Designs in a Nutshell” document on GauchoSpace so that you
have all of the designs in one place to be able to compare them.
Hypothetical study and variables: The effects of marketing (IV) on people’s desire for a product (DV)
Suppose someone wants to argue that a certain marketing strategy increases people’s desire for a
product. Use any marketing strategy you wish for your IV (such as advertising, sponsoring sporting
events, sponsoring social media influencers, product giveaways/discounts, etc.), as well any DV
measure for the effect of the marketing (such as self-reported desire or intent to purchase, the
actual sales in a given period for the product, or something else).
Using the IV and DV above, describe a realistic example of TWO different experimental designs:
Example 1: True Experiment
Choose from one of these true experiments: posttest only control group design, pretest-posttest
control group design, or Solomon four group design
Example 2: Pre-experiment or Quasi-experiment
Choose from one these pre-experiments: one-group pre-test posttest design or static group
comparison; OR choose from one of these quasi-experiments: quasi-equivalent control group
design or one of the times series designs.
For each of your two examples: You can use the design notation (R, X1, Y1, etc.) if it helps you note for
yourself what needs to be included or not (e.g., random assignment, how many groups there are, etc.).
But you also need to be sure to describe your example in words (e.g., “sales figures for the product
before the marketing campaign are compared to…”). Your description should be clear enough that if
someone else read it (without any design notation), they could accurately figure out which design you
described.
In fact, in section you will be sharing your designs (in groups) and then, after perhaps clarifying or
adjusting some things, your group will choose an example to describe to the rest of the class. You will all
be trying to guess/figure out each other’s designs, much like you will need to be able to do on the final
exam!
Example 1: true experiment
For my experiment, I have chosen to do a posttest only control group design to test whether sponsoring
social media influencers increases people’s desire to buy a product. Posttest only control group design
involves two groups, one that watches a video with an influencer promoting the product (X1), and one
who does not watch the promotional video (X2). Then, group X1 and group X2 would be asked how
likely they would be to purchase the product that they viewed the influencer promoting (Y). The ratings
of how likely the two groups were to purchase the product would then be compared to see if the
influencer promoting the product changed participant’s perceptions of the product at all.
Example 2: Pre-experiment
For the pre-experiment, I have chosen to do a one-group pre-test posttest design, which is where there
is one independent variable and two dependent variables. The independent variable is the sponsored
video that the participants are being shown of an influencer promoting a product (X1). The two
dependent variables could be the two groups (Y1 & Y2) that watch the video of the influencer promoting
the product and their ratings of how likely they are to buy the product that was featured in the video.
Both groups of participants would watch the same video but having two groups could be used to gather
more data on how the video affects participants.