Meaning
Probability distributions assigned to the parameters of a multinomial model provide a way to incorporate existing knowledge into market share estimates. Using dirichlet priors allows a researcher to express a belief about the distribution of consumer preferences before any new sales data is observed. This technique is limited to categorical data where the sum of the probabilities must equal one.
Preference Concentration
Estimates of market share for several competing products are often influenced by prior knowledge of the brand landscape. A dirichlet priors approach helps in smoothing these estimates when sample sizes are small by pulling the observed data toward a known average.
Posterior Calculation
Mathematical updates to the initial beliefs occur as new evidence from the marketplace is collected and processed. The combination of the observed data and the dirichlet priors results in a posterior distribution that reflects both historical knowledge and recent trends. This updated model provides a more reliable basis for predicting future consumer choices in a competitive environment.
Data Sparsity
Markets with many small players often lack enough transaction data to build a traditional statistical model for every category. By applying dirichlet priors, the analyst can fill in the gaps for low volume products by using information from the broader market segment. This ensures that the analysis remains stable even when some individual categories have very few sales.