I'm assuming you are speaking in terms of quantitative and qualitative research methods? If so, it depends on the commodity being researched and the market it is entering. I personally appreciate qualitative methods, but sometimes the numbers do make a significant difference in strategic implementation. Hope that helps.
One more thing that, If consumer is in equilibrium position but the price of first commodity will decrease then what will happen? Do the consumer reduce demand for second commodity? for any approach Quantitative Or Qualitative .