Hi, I believe that all of you must have some ideas on the term "Normal Distribution". What I am now facing is a population from batch of power supply output voltage. Since some power supplies had failed in meeting the customer specification at their initial measurement, output were then adjusted by tuning the trim-pot in the power supplies. After that, I measured the output voltage of all the power supplies then drew the distribution graph. You can see that the distribution is now clipped at both ends. Does anyone knows how this kind of distribution called? And, if I cannot use the formula for a normal distribution to calculate the cpk , what can I use to measure the process capability under this condition? Besides, does anyone know something about "Bimodal Distribution" and how is it defined? Comments are welcome. Best Regards, Charles ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################