Unformatted text preview: rnal validity is addressed in the following ways:
• Extraneous factors – eliminated groups take place in the same circumstances and
Changes in subjects – if groups are matched or random, changes will be the same
for all • Measure error – use the same measure – sales of PowerAde • Subjects guessing – no pretest, so no problem • Equivalent groups – use random selection or matching criteria • Drop-out – probably no problem, but should be monitored External validity is taken care of if the groups are representative of all
The test is realistic and generalizable.
BMKT 312 C4 Study Guide 5 14. SplitScreen is a marketing research company that tests television advertisements.
SplitScreen has an agreement with a cable television company in a medium-sized city
in Iowa. The cable company can send up to four different television ads
simultaneously to different households. SplitScreen also has agreements with the
three largest grocery store chains, which will provide scanner data to SplitScreen.
About 25 percent of the residents have SplitScreen scan cards that are scanned when
items are bought at the grocery store and which allows SplitScreen to identify who
bought what grocery products. For allowing SplitScreen access to their television
hook-ups and their grocery purchases information, residents receive bonus points
that can be used to buy products in a special points catalog. Identify and diagram
the true experimental designs possible using the SplitScreen system. Assess the
internal and external validity of SplitScreen’s system.
Application question. This question introduces students to scanner data experimental
design considerations and possibilities.
Virtually any true experimental design is possible with the Split Screen system, but
the most powerful ones would be before-after with control group or after-only design.
The system allows for up to four groups – either four experimental groups or three
experimental groups and one control group. By combining or not using groups,
fewer groups can be used for a less complex design.
All internal validity problems are under control assuming that groups are equivalent,
drop-outs are replaced, commercials are seen at the same time, stores remain
constant, etc. The external validity may concern some students who will point out
the artificiality of the scanner cards, bonus points, and the use of a medium-sized city
in Iowa. If Split Screen recruits households and does not use them right away and
thus lets them settle back into their normal shopping patterns after what might be a
period of unusual shopping because they feel “watched,” the artificiality will be
minimized. The medium-sized city in Iowa is consistent with good market test
selection criteria. BMKT 312 C4 Study Guide 6...
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- Fall '13
- Longitudinal study, Powerade