This is the formula to calculate and produce the Coppock indicator in Metastock:
I do not use Metastock software. I use Insight Trader software. Insight Trader uses Coppock's original method.
As I read it, the Metastock formula above seems to replicate Coppock's original formula, providing Metastock's algorithm for a weighted moving average is the same as Coppock's. However, I dod not use Metastock and this formula was given to me by someone who was a knowledgeable user. I use Insight Trader charting software, which I understand uses the same method as that produced by the Metastock formula. However, there is a small issue I have with both of them:
Coppock also made one additional step, which is not included in the Metastock formula or the Insight Trader method. That was to divide the weighted moving average by 10 and round it to the nearest 10 points. I suspect that Edwin Coppock never did anything without good reason, so this final filter is probably quite important. It seems to me that it filters out small reversals, which are in many cases just short-term "noise".
On my free website (Data and Other Files page on the Free Resources menu), I provide a spreadsheet that calculates the Coppock indicator for the ASX All Ordinaries Index and six other imprtant wold market indices. To make it easier to understand how Coppock calculated the weighted moving average, I have put all the steps across the top of the spreadsheet. It is this way also for those who will update it by hand. It is easy enough to simplify it by writing one formula for many columns if you wish to do so.
I did not recognise the possible importance of the final rounding in Coppock's method at first, so my spreadsheet did not originally include t his step, but the latest version on the website does. If you agree with me that it is important, it may be best to use the spreadsheet number from the last column each month and input it manually into MetaStock. This is not a big task as there is only one number for each month for each index you keep the Coppock indicator for, because the Coppock indicator uses only the monthly closing value of the index.
Alternatively, you can plot the last column in your spreadsheet software, or simply read the signals off the spreadshheet. I post on the website an updated workbook of spreadsheets at the end of every month.