'Advertising and shopping tasks - Online ads with real websites.' (AsPredicted #51740)
Author(s) This pre-registration is currently anonymous to enable blind peer-review. It has 3 authors.
Pre-registered on 2020/11/09 - 06:22 PM (PT)
1) Have any data been collected for this study already? No, no data have been collected for this study yet.
2) What's the main question being asked or hypothesis being tested in this study? A pack-shot in the ad reduces search time compared to an ad without a pack-shot. The reduction in search time is stronger when the shopping website contains competitors that are dissimilar to the target. If the competitors on the shopping website are similar to the target, we expect no or only a weak reduction in search time when people are exposed to an ad with a packshot.
3) Describe the key dependent variable(s) specifying how they will be measured. We will use the natural logarithm of search time as dependent variable
4) How many and which conditions will participants be assigned to? We will use a 2 (pack-shot vs. no pack-shot in ad) x 2 (competing products are similar vs. dissimilar to the target) between subject design. Participants are exposed to four ads and shopping websites (including one example shopping task, which we exclude from the analysis).
5) Specify exactly which analyses you will conduct to examine the main question/hypothesis. We will run a Bayesian regression analysis with the following independent variables:
- pack-shot (yes vs. no), shopping website (homogeneous vs. heterogeneous), and the interaction between them. These variables test our main hypotheses.
- we control for the following: sequence of the shopping task, interaction between sequence and pack-shot, interaction between sequence and homogeneous website, gender, age, and the natural log of time spent on the website with the banner ad.
6) Describe exactly how outliers will be defined and handled, and your precise rule(s) for excluding observations. 1. We will remove participants that are not able to find any of their chosen products in the three main shopping tasks. It is likely that these participants did not pay attention to the instructions.
2. We will remove participants who spent less than 3 seconds on the page with general instructions.
3. We will exclude participants who mention in the open comments that they had reduced vision, could not clearly see the stimuli, or did not understand the instructions.
4. We will remove shopping tasks for which participants spend excessively long or short times on the website with the ad or shopping website (three standard deviations above or below the mean of log search time on either the website with the ad or shopping website).
7) How many observations will be collected or what will determine sample size? No need to justify decision, but be precise about exactly how the number will be determined. We will recruit 801 participants. The sample size is based on power calculations with a significance level of .05 and a power of .80, based on earlier eye-tracking experiments with similar shopping tasks.
8) Anything else you would like to pre-register? (e.g., secondary analyses, variables collected for exploratory purposes, unusual analyses planned?)
