Sequential Analysis

In statistics, sequential analysis or sequential hypothesis testing is statistical analysis where the sample size is not fixed in advance. Instead data is evaluated as it is collected, and further sampling is stopped in accordance with a pre-defined stopping rule as soon as significant results are observed. Thus a conclusion may sometimes be reached at a much earlier stage than would be possible with more classical hypothesis testing or estimation, at consequently lower financial and/or human cost. I. Bross, Sequential medical plans. Biometrics. 1952; 8:186
Syntax: seqanalysis(x)

Inputs: X - Nx2 data matrix Outputs:

Sequential analysis plots

Example: During a sperimentation between two terapies, two drugs A and B were administered to patients couples (one received A, the other B). A positive result in a patient by the drug is indicated by 1; a negative result by 0. Result are resumed in this table:

Couple A B Note 1 1 1 Non informative 2 1 0 All for A 3 0 0 Non informative 4 1 0 All for A 5 1 0 All for A 6 1 1 Non informative 7 0 1 All for B 8 1 1 Non informative 9 1 0 All for A 10 1 0 All for A 11 1 0 All for A 12 1 1 Non informative 13 1 0 All for A 14 0 1 All for B 15 0 0 Non informative 16 1 0 All for A 17 1 0 All for A 18 1 0 All for A 19 1 1 Non informative 20 1 0 All for A

The algorithm will discard all non informative couple; then, it will start to move along the chart. If it goes out the twilight zone, the sperimental plan can be stopped and non more couple will be required. To test the function with these data: x=[1 1; 1 0; 0 0; 1 0; 1 0; 1 1; 0 1; 1 1; 1 0; 1 0; 1 0; 1 1; 1 0; 0 1; 0 0; 1 0; 1 0; 1 0; 1 1; 1 0]; seqanalysis(x)

Created by Giuseppe Cardillo
giuseppe.cardillo-edta@poste.it

To cite this file, this would be an appropriate format: Cardillo G. (2008) Sequential analysis test. http://www.mathworks.com/matlabcentral/fileexchange/22204