A Venn diagram is a logical tool that uses a series of geometric shapes, each representing a specific condition, drawn partially overlapping each other. In each region, the conditions are evaluated separately in order to give you a visual demonstration of your solutions. For instance, if you were making a simple Venn diagram to evaluate the cost of a date, you could use two circles with one representing the cost of a movie and the other representing the cost of dinner. In the region where they overlap, you could see the total cost of doing both.
Brainstorming is a tool for evaluating a question or condition through free association and connecting conditions. You begin by writing your question in the middle of a page, writing other questions or situations extending from your main question around it and drawing lines to connect each. Repeat the process by using every extended question or condition as a new starting point. Build your brainstorming map from the center out, focusing on unclear questions or connections as you arrive at them.
A pro/con list is a problem-solving tool that specializes in assisting you when making yes or no decisions. Draw a line down the center of a sheet of paper. On one side, write the word "yes" and on the other write the word "no." Use the area below these words to write the reasons you should do something and the reasons you should not. When you finish, you can evaluate your question by adding the pros and the cons or by evaluating the overall benefits of a decision against the overall disadvantages.
A cost-benefit analysis is the process of adding together the costs associated with a decision and comparing this figure to the total potential benefit of the decision. Statistical math helps you evaluate these benefits. As an example, if you add up the potential cost of an investment, you can compare this number to the result of multiplying the potential result of the investment by the percentage chance of achieving this benefit. While speculative, businesses use this model to evaluate potential investments and business improvements.