Yup. I always advocate that the first model one should build is the one that constantly returns the most common answer. That way, you can compare the more fanc

Yup. I always advocate that the first model one should build is the one that constantly returns the most common answer. That way, you can compare the more fancy stuff to something to see whether you're really improving. You also get to evaluate the economic gains of the more sophisticated model against the development, maintenance, and data costs of it, compared to the dumb one. (Another good baseline is returning a random historic result in proportion to how often it occurs. It sometimes helps against exploit attempts at the expense of data.)