Fig. 2.

Screenshot of new online tool that can be used to calculate P values testing the hypothesis of whether one binary outcome clusters in the middle of a (1D) sequence of binary outcomes. One input method is simply typing two characters in a text box (above, “U” for up and “D” for down) and letting the calculator return a P value showing whether one type of character is clustered in the middle. To test whether the other type of character is clustered, the “SWAP” button can be used. The hypergeometric walk is shown graphically. The exact P value, computed with the methods in this article, is shown. The two Hogan–Siegmund approximations for this P value are also shown.