In the Journal of Marketing Research (November 1996), Gupta studied the extent to which the purchase behavior of scanner panels is representative of overall brand preferences. A scanner panel is a sample of households whose purchase data are recorded when a magnetic identification card is presented at a store checkout. The table below gives peanut butter purchase data collected by the A. C. Nielson Company using a panel of 2,500 households in Sioux Falls, South Dakota. The data were collected over 102 weeks. The table also gives the market shares obtained by recording all peanut butter purchases at the same stores during the same period. Brand Size Number of Purchases by Household Panel Market Shares Jif 18 oz. 3,165 20.10% Jif 28 1,892 10.10 Jif 40 726 5.42 Peter Pan 10 4,079 16.01 Skippy 18 6,206 28.56 Skippy 28 1,627 12.33 Skippy 40 1,420 7.48 Total 19,115 Goodness-of-Fit Test obs expected O – E (O – E)2/E % of chisq 3165 3842.115 –677.115 119.331 13.56 1892 1930.615 –38.615 0.772 0.09 726 1036.033 –310.033 92.777 10.54 4079 3060.312 1018.689 339.092 38.52 6206 5459.244 746.756 102.147 11.60 1627 2356.880 –729.880 226.029 25.68 1420 1429.802 –9.802 0.067 0.01 19115 19115.000 0.000 880.216 100.00 (b) Determine whether the purchase behavior of the panel of 2,500 households is consistent with the purchase behavior of the population of all peanut butter purchasers. Assume here that purchase decisions by panel members are reasonably independent, and set α = .05. (Round your answers x2 to 2 decimal places and x2.05 to 3 decimal places.)
In the Journal of Marketing Research (November 1996), Gupta studied the extent to which the purchase behavior of scanner panels is representative of overall brand preferences. A scanner panel is a sample of households whose purchase data are recorded when a magnetic identification card is presented at a store checkout. The table below gives peanut butter purchase data collected by the A. C. Nielson Company using a panel of 2,500 households in Sioux Falls, South Dakota. The data were collected over 102 weeks. The table also gives the market shares obtained by recording all peanut butter purchases at the same stores during the same period. |
Brand | Size | Number of Purchases by Household Panel |
Market Shares |
Jif | 18 oz. | 3,165 | 20.10% |
Jif | 28 | 1,892 | 10.10 |
Jif | 40 | 726 | 5.42 |
Peter Pan | 10 | 4,079 | 16.01 |
Skippy | 18 | 6,206 | 28.56 |
Skippy | 28 | 1,627 | 12.33 |
Skippy | 40 | 1,420 | 7.48 |
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Total | 19,115 | ||
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Goodness-of-Fit Test | |||||
obs | expected | O – E | (O – E)2/E | % of chisq | |
3165 | 3842.115 | –677.115 | 119.331 | 13.56 | |
1892 | 1930.615 | –38.615 | 0.772 | 0.09 | |
726 | 1036.033 | –310.033 | 92.777 | 10.54 | |
4079 | 3060.312 | 1018.689 | 339.092 | 38.52 | |
6206 | 5459.244 | 746.756 | 102.147 | 11.60 | |
1627 | 2356.880 | –729.880 | 226.029 | 25.68 | |
1420 | 1429.802 | –9.802 | 0.067 | 0.01 | |
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19115 | 19115.000 | 0.000 | 880.216 | 100.00 | |
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(b) |
Determine whether the purchase behavior of the panel of 2,500 households is consistent with the purchase behavior of the population of all peanut butter purchasers. Assume here that purchase decisions by panel members are reasonably independent, and set α = .05. (Round your answers x2 to 2 decimal places and x2.05 to 3 decimal places.) |
χ2 |
Given information:
Brand | Observed | Market share |
Jif 18 oz | 3165 | 20.1% |
Jif 28 oz | 1892 | 10.1% |
Jif 40 oz | 726 | 5.42% |
Petern Pan 10 oz | 4079 | 16.01% |
Skippy 18 oz | 6206 | 28.56% |
Skippy 28 oz | 1627 | 12.33% |
Skippy 40 oz | 1420 | 7.48% |
Sum | 19115 | 100% |
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