METHODS AND APPARATUS TO PERFORM CHOICE MODELING WITH SUBSTITUTABILITY DATA

1 . A method to calculate choice probability, comprising:

receiving base choice probability values for a respondent, wherein the base choice probability value is associated with a product;

receiving a respondent substitutability factor associated with the product;

identifying, with a cluster analysis engine, a primary product and a secondary product and generating a subrespondent associated with the secondary product; and

calculating, with a cross sourcing engine, a modified choice probability for the subrespondent for the secondary product based on the respondent substitutability factor and the base choice probability values associated with the secondary product.

2 . A method as described in claim 1 , further comprising calculating a modified choice probability for the subrespondent for the primary product based on the base choice probability values associated with the primary product and the modified choice probability of the secondary product.

3 . A method as described in claim 1 , wherein the primary product and the secondary product are associated with a common category and different subcategories.

4 . A method as described in claim 1 , further comprising performing a card sort to obtain information indicative of substitutability between the primary product and the secondary product.

5 . A method as described in claim 4 , further comprising generating a triangular matrix with the information indicative of substitutability to calculate a relative similarity distance between the primary product and the secondary product.

6 . A method as described in claim 1 , further comprising performing a virtual shopping exercise using a multinomial logit model to generate the base choice probability values.

7 . A method to calculate choice probability, comprising:

performing a card sort for products within a category using a card sort engine, the card sort engine retrieving information indicative of product similarity;

generating, with a substitutability matrix engine, a triangular matrix with the information indicative of product similarity;

transforming the triangular matrix into a list of product subcategories;

calculating substitutability values between the subcategories based on matrix values for pairs of products selected between product subcategories; and

invoking a multinomial logit model to generate choice probabilities based on the substitutability values and a virtual shopping exercise.

8 . A method as described in claim 7 , wherein the triangular matrix increments a product pair cell value in response to a card sort indication of similarity between a first product and a second product.

9 . A method as described in claim 8 , further comprising adding product pair cell values for each product subcategory pair and dividing by a number of product pairs and a number of respondents to calculate the substitutability values.

10 . A method as described in claim 7 , wherein invoking the multinomial logit model generates choice probability values based on a degree of substitutability between the product pairs.

11 . A method as described in claim 7 , wherein the substitutability values suppress independence of irrelevant alternatives.

12 . An apparatus to calculate choice probability, comprising:

a card sort engine to generate information indicative of product similarity;

a substitutability matrix engine to generate a triangular matrix with the information indicative of product similarity;

a cluster analysis engine to identify product subcategories within the triangular matrix and calculate substitutability values between the subcategories based on matrix values for pairs of products selected between product subcategories; and

a cross sourcing engine to implement a multinomial logit model to generate choice probabilities based on the substitutability values and a virtual shopping exercise.

13 . An apparatus as described in claim 12 , wherein the substitutability matrix engine increments a product pair cell value in response to a card sort indication of similarity between a first product and a second product.

14 . An apparatus as described in claim 13 , wherein the substitutability matrix engine further comprises adding product pair cell values for each product subcategory pair and diving by a number of product pairs and a number of respondents to calculate the substitutability values.

15 . An apparatus as described in claim 12 , further comprising a discrete choice exercise engine to invoke the virtual shopping exercise.

16 . A tangible article of manufacture storing machine readable instructions that, when executed, cause a machine to at least:

receive base choice probability values for a respondent, wherein the base choice probability value is associated with a product;

receive a respondent substitutability factor associated with the product;

identify, with a cluster analysis engine, a primary product and a secondary product and generating a subrespondent associated with the secondary product; and

calculate, with a cross sourcing engine, a modified choice probability for the subrespondent for the secondary product based on the respondent substitutability factor and the base choice probability values associated with the secondary product.

17 . A tangible article of manufacture as described in claim 16 , wherein the machine readable instructions, when executed, cause the machine to calculate a modified choice probability for the subrespondent for the primary product based on the base choice probability values associated with the primary product and the modified choice probability of the secondary product.

18 . A tangible article of manufacture as described in claim 16 , wherein the machine readable instructions, when executed, cause the machine to perform a card sort to obtain information indicative of substitutability between the primary product and the secondary product.

19 . A tangible article of manufacture as described in claim 18 , wherein the machine readable instructions, when executed, cause the machine to generate a triangular matrix with the information indicative of substitutability to calculate a relative similarity distance between the primary product and the secondary product.

20 . A tangible article of manufacture as described in claim 18 , wherein the machine readable instructions, when executed, cause the machine to perform a virtual shopping exercise using a multinomial logit model to generate the base choice probability values.