I'm working on a public procurement dataset where I have information on all the participants that presented offers in 358 tenders. I'm analysing relationships between all the companies of the dataset (1242). For each dyad (pair of companies) I'm calculating:
a) the number of times they participated together, and
b) the number of times they submitted exactly the same offer.
I am unsure about the b) measure. When I calculate it, I obviously get missing values everytime two companies did not participate together in a tender and so did not have the "opportunity" to submit the same offer. This variable seems to create problems in regression because of the many missing values. I thought that I could fill missing values with "0", thus without conditioning this variable to co-bidding in the same tender. Do you think this approach makes sense or is it a way to force the data too much?