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YORAM WIND and RONALD E. FRANK*

This article reports pairwise correlation coefficients between 38 grocery productsbased on two different measures of household brand purchasing behavior. Themodest magnitude of these coefficients implies that situation-specific as opposed togeneral household characteristics are the best candidates for predicting bran d buyingbehavior within products.

Interproduct Household Loyalty to Brands

INTRODUCTIONAre households that exhibit an above average level ofloyalty to brands in one product category also likely todo so in other categories? That is, do households tendto be loyalty prone regardless of the product involved?The degree to which household loyalty to brands iscorrelated over products has important implications forthe design of research aimed at understanding and pre-dicting household purchasing behavior. The existence ofa tendency for the same household to be loyal acrossmany products at a point in time implies that the de-terminants of brand loyalty are general as opposed tosituation-specific household characteristics. Generalcharacteristics are those which have little or no connec-tion with either customer attitudes or behavior towardthe product being analyzed, such as personality, socio-economic and demographic characteristics. In contrast,situation-specific household characteristics are thosedirectly related to the product under investigation. Forexample, if one were studying loyalty to cereal brands,situation-specific characteristics might include a cus-tomer's attitude toward the product and the number ofbrands of cereal available in stores frequented by thecustomer.The greater the correlation of household loyalty tobrands over products: (a) the more important are apt tobe general as opposed to situation-specific customercharacteristics as determinants of brand loyalty, and (b)the more likely it is that one can develop a set of house-hold characteristics useful for classifying households forvarious purposes such as media selection and marketsegmentation, regardless of the product category in-volved.Published research bearing directly on this question is

* Yoram Wind is assistant professor of marketing and RonaldE. Frank is professor of marketing, University of Pennsylvania.

exceedingly sparse. Based on a study of grocery productcategories in 1956, Cunningham concluded that:Those [housewives or other household purchasers]who are highly loyal to a brand of one product mayhave very little loyalty to a brand of another product[ ] , p . 117].

Massy, Frank and Lodahl reached the same conclusion,based on a study of household purchasing behavior forbeer, coffee and tea [2, pp. 6 6 - 9 ] .The objective of this study is to measure the degreeto which household brand loyalty is correlated from oneproduct category to another. It is differentiated from pasresearch by the fact that it is based on household pur-chasing behavior for 38 grocery products in contrast tothe nine categories used by Cunningham and the threeused in the Massy, Frank and Lodahl study.

THE DATAThe data were obtained from the Chicago Tribuneconsumer panel for the year 1961. The data base in-cludes records of over 400,000 purchases. For eachhousehold purchase, a record was made showing theproduct category, the date of purchase, the brand purchased, the store patronized, and the kind and extent ofdeal involved, if any.In the original data base were included 59 frequentlypurchased household products. This set of products wasscreened twice to eliminate those products that:

1. were purchased by only a small number of families2. were bought more than four times by only a smalpercentage of households.The first test reduced the number of products from 59to 44 and the second from 44 to 38. T'he remaining 38products comprise a diverse cross section of household

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Journal of Marketing Research,Vol. VI (Novem ber 1969), 434-3

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INTERPRODUCT HOUSEHO LD LOYALTY TO BRANDS 4 3 5prod ucts such as regular coffee, all-purpose flour, cannedmilk, margarine, peanut butter, cereal, liquid detergents,canned peaches, toilet tissue, and packaged desserts.

METHODSeparate analyses were conducted b ased on two differ-ent measures of household brand purchasing behavior.Measurements were taken on each product and are de-flned as follows:

1. Brand Loyalty. The percentage of purchases madeby a household of the brand it bought most oftenduring 1 961.2. Private Brand Proneness. The percentage of pur-chases made by a household devoted to privatebrands. (A private brand is defined as one which isowned by a retailer, distributor, or packer.)For each measure of brand buying behavior, thesimple coefficient of determination (the square of thesimple correlation coefficient) between every pair of

products was computed and summarized.^FINDINGS

The results of the pairwise coefficient of determinationanalysis are presented in Table 1, which reports thefrequency distribution of the pairwise coefficient of de-termination (sign ignored) for brand loyalty and privatebrand proneness. The average pairwise coefficient of de-termination is only .029 for brand loyalty and only .038for private brand proneness. On the average, only anextremely small percentage of the variation from house-hold to household in loyalty to brands in one productcategory is associated with variation in brand loyaltyin another category.This implies that situation-specific as opposed to gen-eral characteristics are apt to have the greatest potentialfor predicting household loyalty to brands within aproduct category. One might reasonably argue, however,that though the average pairwise correlation coefficientsare quite low, nonetheless there are likely to be subsetsof products that:

1. can be identified based on the researcher's a prioriknowledge.2. Will have reasonably high pairwise coefficients ofdetermination.Stated another way, one might argue that the degree

of generality for general characteristics might be limitedto certain subsets of products, e.g., those which are rela-tively similar in terms of their end use. The three mostsimilar products included in our data base were regularcoffee, soluble coffee, and tea . The ir pairwise coefficientsof determination were:^ Factor analyses of both the brand loyalty and private brandproneness correlation matrices were run. However, the resultsprovided no further insight than was gained from the simplecorrelation coefficients and the authors' prior knowledge of theproducts and are therefore not reported.

Product pairRegularsoluble coffeeSoluble coffeeteaRegular coffeetea

Brandloyalty.04.19.04

Privatebrandproneness

.12.05.05These figures are higher than the averages presentedin the table, but nonetheless are still quite modest inmagnitude. The same is true of other products whichon one or another a priori basis one might considersimilar. In fact, the highest pairwise coefficients of de-termination occurred between pairs of products forwhich, in our opinion, there is no clear rationale. Forexample, the highest pairwise coefficient of determina-tion for brand loyalty was .28 for all-purpose flour andsoluble coffee. T'he highest coefficient of the privatebrand proneness analysis was .40 for ready-to-eat cerealand canned peaches.

FREQUENCY DISTRIBUTION OF COEFFICIENTS OFDETERMINATION FOR PAIRWISE PRODUCT CO MP ARISO NS

Coefficient ofdeterminationPercent ofcases forbrand loyalty

Percent of casesfor private brandpronenessO-.OlO.011-.050.051-.100.101-.150.151-.200.201-.250.251-.300.301-.350.351-.400

TotalBase

29.7351.2116.502.420.140

100.00703

CONCLUSION

35.1437.8416.796.122.840.570.140.280,28100.00703

The presence of relatively modest pairwise coefficientsof determination does not provide direct evidence on therelative importance of general versus situation dependenthousehold characteristics. Yet, the lack of interproducthousehold loyalty to brands suggests that general charac-teristics are not apt to be highly correlated with house-hold loyalty to brands. Effort should focus on the designof measurement instruments that measure householdcharacteristics such as preferences, perceptions andbrand distribution, that are related to both the house-hold and product under investigation, and not to thehousehold alone.R E F E R E N C E S

1. Ross M. Cunningham, "Brand LoyaltyWhat, Where, HowMuch," Harvard Business Review, 34 (January-February1956), 116-28.2. William F. Massy, Ronald E. Frank and Thomas Lodahi,Purchasing Behavior and Personal Attributes, Philadelphia:University of Pennsylvania Press, 1968.

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