In a past life I tried to normalize this by adding the standard deviation of the rolling averages. And then triggered off of the new average. I also do not use rework in yield calculations at all. The yield info is first pass data. Kat >>> [log in to unmask] 12/27/02 12:09PM >>> Does anyone have a standard way to normalize yield percentage charts for wildly varying production volumes ? My yield percentage charts show 50% yield when there is 1 out of 2 failures or 50 out of 100 failures. The 50% Yield with 1 out of 2 usually happens during a Christmas week when there is no production, only rework. I have tried to normalize the charts by using a constant denominator based on the nominal volume. I use 13 week rolling averages but they are messed up by the low volume yield results. This low volume percentage reporting can cause incorrect corrective actions. Does anyone know of a standard way to normalize the data ? Cronbach's Alpha, Split-Half Reliability (Spearman-Brown Coefficient), Attenuation correction, Pair Wise Deletion of Missing Data, Partial correlation, Parzen Window, Pearson Curves, Johnson Curves ? Paul Signorelli --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------