Pricing research: single vs. multiple presentations
Data gathered through multiple presentation methods can produce significantly different results than single presentations to separate, matched samples.
Background:
Researchers must contend with the possibility that a response to a question may be influenced in some way by preceding questions. Such contamination, should it occur, might result in faulty marketing recommendations.
This study will focus on potential questioning contamination as it applies to pricing research. Can two or more price options be presented to a single sample without contamination of results? or, is a single price presentation to separate matched samples a mandatory requirement?
The multiple presentation method is a frequently chosen technique in market research. It is less expensive than a single presentation method since only one sample is employed, and so appears cost effective.
The case for multiple presentations is further enhanced by other arguments advanced in its favor.
- The technique usually provides a statistically more robust sample base than split samples.
- A multiple presentation method isolates three sub-groups of respondents for analysis;
- those who are price sensitive (they choose the item only at the low price option)
- those who choose the item at both prices
- those who do not choose it at either price
- Researchers contend that any order bias can be averaged in the final data processing, as long as versioned questionnaires are used.
The problem researchers must face is this: Do multiple presentations produce different results than single presentations? If significantly different results occur, the extra expense contingent upon a single presentation procedure may be warranted. Differing results would indicate that averaging of bias is not a sufficient safeguard against contamination. Data contamination might also mitigate any statistical advantage inherent in a multiple presentation procedure.
Research Method:
Two data gathering methods were chosen. One was a multiple presentation method in which two price options for a product were presented. The second was a single presentation procedure in which only one price option was presented. Two questionnaire versions were developed for the multiple presentation technique, and administered to two balanced samples. In one version the low price options were presented first, the high price options second. This order was reversed for the second version. Results were averaged to offset order bias effects. The second technique, a single presentation procedure, employed two balanced, independent samples, each receiving only one price option.
Test questions consisted of a willingness to purchase scale for two products: a diesel engine and a window washing cloth. These items were chosen since respondents might react differently to an expensive product than they would to an inexpensive one. Thus, the effects of the relative price of a product, as well as the effects of the two data gathering procedures could be ascertained.
The multiple presentation questionnaires contained the following items:
-
A quiet diesel engine that uses fuel which costs 10% less than gasoline and gets 20% more
miles per gallon than comparable gasoline powered engines. This diesel engine would cost
an additional $1,200 over the cost of the regular engine, For $1,200 more, what would you do?
- Definitely would buy the diesel
- Probably would buy the diesel
- Probably would not buy the diesel
- Definitely would not buy the diesel
-
This specially treated cloth will clean glass without water and special cleaners. The
cloth is guaranteed to clean at least 1000 average size windows.
You could buy the cloth for 39¢.- Definitely would buy it
- Probably would buy it
- Probably would not buy it
- Definitely would not buy it
In version one the items were presented as seen above, low price options first, high price options second. In the second version order of presentation was reversed .
The single presentation questionnaires contained only one price option for each product. One sample was asked if they would purchase the diesel engine for $1,200 and the window washing cloth for 39¢. The other sample was presented with the high priced options, $1,500 for the diesel engine and 59¢ for the window washing cloth.
All questionnaires contained identical control questions. Test questions followed the control questions in every case.
Results:
The two methods produced significantly different results for the window washing cloth. Respondents presented with single price options show an equal willingness to purchase the window washing cloth at either price. Apparently, increasing the price from 39¢ to 59¢ has little effect on respondents' willingness to purchase this item. This finding holds for both "top—box" and total "would—buy" scores. The data suggest that demand for this product is inelastic with in the price levels studied. This is in direct contrast to the multiple presentation results which suggest a strong elasticity of demand for this product.
Claimed interest for the diesel engine was not affected whether multiple or single questioning procedures were employed. Respondents surveyed by either technique showed about an equal willingness to purchase this product.
Conclusions:
The results confront researchers with an anomaly. The two methods produce significantly different results for the window washing cloth, while producing similar results for the diesel engine.
Apparently, multiple presentations biased responses to the window washing cloth, but not to the diesel engine. Whether this effect holds generally for high vs. low priced products, or is due to the nature of the products studied cannot be generalized from the available data. However, the results do suggest that a multiple presentation method may introduce biasing effects not present in a single presentation procedure.
Thus, though apparently cost effective in the short-run, multiple presentation procedures may lead to long-run disadvantages. Decisions based on contaminated data could prove extremely costly.
Caution is advised in generalizing these findings. The results may only be valid for self administered questionnaires, and perhaps, only for the products studied.
