Choose the total sample size, the grand total of all four cells in the contingency table.
Also choose the experimental design:
•Cross-sectional. You sample subjects without regard to their exposure or disease.
•Prospective. You choose subjects based on exposure defined by the rows, and then inquire about outcome defined by the columns.
•Experimental. You assign treatments that define the row, and then tabulate outcome that defines the columns.
•Case-control-retrospective. You choose cases (with disease) and controls and these define the columns. You then look back at exposure and tabulate these results into rows.
Enter titles for both rows and both columns.
Enter various probabilities as asked. The details depend on the experimental method you chose.