How to evaluate how a certain novel is performing is quite tricky since there aren't any electronic devices to make things easier, but still, there are some ways to make it somewhat possible.
A small letter-sized questionnaire is shipped in with the newspaper for the readers to hopefully read the novel and fill it and hopefully post it to the newspaper office, which again, hopefully using the companies premium client privilege, the local post office collects all the questionnaires and brings them to the office in a few hours.
There are a lot of hopefullys in the scenario, but in the end, considering the era, it is a miracle that this is even possible.
