Idea is the beginning and the most important ingredient of data analysis. Idea is the context and purpose of analysis. Analyzing data without an idea is aimless and a waste of time.

If sales of a particular product are declining, a sales manager might have an idea to look at sales staff performance, or she might have an idea about product cannibalization, or she might have an idea nobody heard of before. A manager may have an idea about how to improve marketing campaign response rate. A doctor may have an idea for more effective treatment of cancer. These ideas lead to data requests in order to obtain empirical evidence.

Subject matter expert (SME) must first have an idea about what data to analyze, how to analyze it and why.