Suppose you come across the following paragraph in a research paper or Honours Thesis.

85.7% of the school teachers surveyed said that they use problem-solving questions instead of essay questions in student assessment. A scrutiny of the exams they have set confirms that they do use problem-solving tasks and not essays. This supports our hypothesis that the majority of school teachers use problem solving and not essay questions in student assessment.

To make an informed decision on whether the grounds cited in this argument justify the conclusion or not, you would need to know more about the survey. Mention two important pieces of information you need to have before you can form a judgment, and say why they are important.