CUSUM involves the calculation of a cumulative sum - a sequence analysis technique used for monitoring change. The Foresee CUSUM calculator allows you to examine a standard process and using bootstrapping techniques draws the control lines.
First describe the series of successes and failures using the standard procedure.
• S - Represents a positive outcome (success)
• F - Represents a negative outcome (failure)
Next fill in the number of iterations of bootstrapping desired. (doing more than 1000 iterations takes more computer time)
Click the button to 'randomize'
This may take a few minutes, during which your browser may be unresponsive.
The Foresee calculator will calculate the weight for each S and F in the original cohort.
It will also rearrange the sequence in random order and calculate the minimum (lower) and maximum (upper) value for each of the iterations.
Then the mean and SD for all the lower and upper values are calculated for the upper and lower limits - this information is displayed.
Use the 'S' and 'F' buttons to enter your new trial data. A graph will appear with a green line showing a value that is +2 SD above the average of the upper limits, and a red line representing a value -2 SD below average of the lower limits.
The successand failures can be fed in as the experiment proceeds and the CUSUM, in real time, can be noted.
By default the control lines are set at 2SD but the lower and upper control lines can be set at different SD depending on ones needs.
Use the 'Restart' button at the top of the page to re-set the applicaiton.
Use the 'Printable View' to show a larger graph, and a summary of the data used.
http://jacob.puliyel.com/foresee | © 2009 Jacob Puliyel / Ashish Puliyel