Question

For each description, generate a simple causal explanation of the results based on the variables in the description (Note that in a couple of cases, only a pretest and posttest are described with no treatment or intervention between them). Then, identify the threat or threats to internal validity that could provide an alternate explanation for the results, and briefly explain how it or they would explain the results.

1. An advertiser develops a new ad campaign for somewhat popular 60-inch plasma TVs. A year after the ad campaign is begun, sales for these TVs have dropped substantially.

Answer 1

Plasma fizzles, campaign a dud? Maybe. But market tides, rival's flood, or recession's chill could explain the thrill. Dig deeper, threats to heed, unveil the story, truth concealed.

Description 1: Plasma TV sales decline after new ad campaign

Causal explanation: There are several possible explanations for why plasma TV sales might have dropped after the new ad campaign:

Campaign ineffectiveness: The ad campaign could have been ineffective in promoting the TVs, potentially due to poor messaging, targeting the wrong audience, or simply ineffective media channels.

Market saturation: The market for 60-inch plasma TVs might have become saturated, leading to a general decline in sales regardless of the ad campaign.

Competition: New technologies or competitor brands might have gained traction, attracting consumers away from 60-inch plasma TVs.

Economic factors: Changes in the economy, such as a recession, could have reduced consumer spending on high-priced electronics.

Threats to internal validity: Several threats could provide an alternate explanation for the results:

History: Events unrelated to the campaign, such as economic changes or competitor actions, could have caused the sales decline.

Maturation: Changes in consumer preferences over time could explain the shift away from plasma TVs, regardless of the campaign.

Testing: If the pre- and post-campaign measurements weren't comparable (e.g., different marketing efforts before the campaign), it's difficult to isolate the campaign's effect.

Regression to the mean: If plasma TV sales had been unusually high before the campaign, they might have naturally trended back down regardless of the ad effort.

Therefore, while the new ad campaign could have contributed to the decline in plasma TV sales, other factors and internal validity threats must be considered before drawing a definitive conclusion.

Note: This example only analyzes a posttest without a pretest or treatment, making it difficult to establish reliable causality.

For situations with pretests and treatments, the analysis would go further by comparing changes in the treatment group with those in the control group and considering additional threats like selection bias, Hawthorne effect, and instrumentation.