Olestra is a fat substitute that was used many years ago particularly in potato chips. In the U.S. it was banned due to reports of gastrointestinal (stomach) upset from consuming products containing olestra. There were studies done to test whether or not olestra caused gastrointestinal upset. In one study, they found that 38.2% persons in the olestra group and 36.9% of the controls reported at least one gastrointestinal upset (P = 0.60). What does this P-value mean