McDaniel & Gates – Marketing Research, 9th Edition Instructor’s Manual
B. Examples of Quasi-Experiments
1. Interrupted Time-Series Designs–repeated measurement of an effect both before and after a
treatment is introduced that “interrupts” previous data patterns
O1 O2 O3 O4 X O5 O6 O7 O8
a. Primary Weakness–inability to control history and possibility of interactive effects of testing
2. Multiple Time-Series Designs–interrupted time-series design with a control group–shown
symbolically as follows:
Experimental Group: O1 O2 O3 O4 X O5 O6 O7 O8
Control Group O1 O2 O3 O4 O5 O6 O7 O8
See Global Research: What Happens When Your Selection Bias Is the Interviewer’s
Gender? (pg. 255)
Recently, German researcher Stefan Althoff found that surveys sent by women or with women’s
names get better responses than men’s.
• In 2004, Lufthansa Technik in Hamburg, Germany commenced an online customer survey and
observed a very low response. A week later they sent out reminders, but this time the writer
• In March, 2006, the researchers surveyed 460 registered users of UNIpark and split them into
four groups and asked them to evaluate UNIpark’s Web site homepage and the utility of
Discussion Questions:
1. What types of possible (even if subtle) bias might result from male respondents answering an
e-mail survey sent or signed by a female?