A multiple discriminant analysis was conducted to determine if respondents’ attitudes to the Tylenol brand affected whether the respondents were “up-movers” or “down-movers.” “Up-movers” are those respondents who had a positive change score for Tylenol on the constant sum scale after viewing the advertisements, while “down-movers” had a negative score. The categorical dependent variable is group membership, while the independent variables are the scores on the ten brand attitude Likert items. The sample is drawn from 126 respondents.
Note: None of the brands under consideration provided an ideal, relatively balanced distribution of up- and down- movers for discriminant analysis. Even if non-movers were added to one group or the other, the numbers of the groups would be very lopsided. Tylenol was selected as the brand with the smallest difference between up-movers and down-movers.
Table 1: Tylenol brand attributes
Tylenol... |
Up-movers |
Down-movers |
Unstandardized discriminant function coefficient |
Standardized discriminant function coefficient |
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Mean |
Standard deviation |
Mean |
Standard deviation |
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...is a good brand |
4.0 |
0.8 |
4.1 |
0.6 |
0.3 |
0.2 |
...works fast |
3.5 |
0.9 |
3.7 |
0.8 |
0.2 |
0.2 |
...prevents heart attacks |
2.8 |
0.7 |
2.8 |
0.8 |
0.0 |
0.0 |
...is safer |
3.3 |
0.8 |
3.1 |
0.8 |
-0.7 |
-0.5 |
...is trustworthy |
3.7 |
0.8 |
3.9 |
0.9 |
-0.0 |
-0.0 |
...would be prescribed by my doctor |
3.6 |
0.7 |
3.6 |
0.9 |
0.3 |
0.3 |
...is easy to use |
4.1 |
0.6 |
4.0 |
0.9 |
-0.5 |
-0.5 |
...doesn’t have too many side effects |
3.6 |
0.8 |
3.8 |
0.8 |
0.6 |
0.5 |
...is made by a company that cares about my health |
3.4 |
0.7 |
3.2 |
0.8 |
-0.8 |
-0.6 |
...provides effective pain relief |
3.8 |
0.8 |
4.0 |
0.6 |
0.7 |
0.5 |
Down movers sample size: 42, Up movers sample size: 26 |
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In the above table, none of the mean Likert scores for each attribute varies more than 0.2 points between up-movers and down-movers – thus there appear to be few if any great differences between the two groups’ perceptions of the Tylenol brand. “Tylenol is safer than other over-the-counter pain relief medications, “Tylenol would be prescribed by my doctor,” “Tylenol is easy to use,” “Tylenol is made by a company that cares about my health” and “Tylenol provides effective pain relief” appear to be the most important brand attributes in determining whether respondents were up movers or down movers.
Table 2: Group centroids and inferential statistics
Group |
Average discriminant score |
Up movers |
-0.4 |
Down movers |
0.2 |
Wilks’s Lambda |
Chi-squared |
0.93 |
4.61 |
|
* p ≤ 0.15 |
The Wilks’s Lambda test, when converted to Chi-squared, is not statistically significant. Thus it would not necessarily be expected that in 85 samples out of 100 samples drawn from the same population as this sample, the difference between the up movers’ and down movers’ group centroids would be what it is here. The group centroids cannot be projected to the larger population.
At 0.6, the difference between the average discriminant scores of up movers (-0.4) and down movers (0.2) is not great and not statistically significant.
Table 3: Classification matrix
Actual membership |
Predicted membership |
|
Up movers |
Down movers |
|
Up movers |
8 |
18 |
Down movers |
7 |
35 |
63.2% of original grouped cases correctly classified |
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According to the classification matrix, only 43 respondents out of 68 (63.2%) fall into their predicted groups.
Table 4: Significance of classification matrix
t |
1.57* |
* p ≤ 0.15 |
Although 63.2% is not far above chance levels, the percentage of original grouped cases correctly classified is statistically significant. In 85 samples out of 100 samples drawn from the same population as this sample, it would be expected that the percentage of cases correctly classified would be about what it is here.
