I need to create bollinger bands in Numbers
I am trying to chart a performance margin on a chart. I tried to chart a shaded area around a moving average using plus an minus STDEV's but the problem is that the STDEV cant show a negative number and this moving average travels into negative territory. Below is what i have.
for the moving average: =SUM(X815:X838)/25
For the top and bottom areas for the shaded area: =AC839+STDEV(AC815:AC838)
=AC839-STDEV(AC815:AC838)
iMac, Mac OS X (10.6.7)