EWMA - Regelkarte

[#1]

Hey!

I would like to plot the following expression but I have some problems with the second therm:

.

Here I copy the explanation of the formula:

"The EWMA chart computes successive observations z_i by computing the rational subgroup average, , and then combining that new subgroup average with the running average of all preceding observations, z_{i - 1}, using the specially–chosen weight, λ."

My Data looks like this:

Date	Value
2012.01.03 16:03:55	0,41
2012.01.03 20:31:43	0,434
2012.01.03 23:13:58	0,42
2012.01.04 13:56:06	0,431
2012.01.04 16:21:06	0,455
2012.01.04 22:14:28	0,45
2012.01.04 22:20:31	0,437
2012.01.04 22:26:45	0,448
2012.01.04 22:35:22	0,437
2012.01.04 23:16:09	0,449
2012.01.11 10:10:07	0,449
2012.01.11 10:37:04	0,422

The subgroups must be "days".

Thank you very much!!! This chart is driving me crazy!

Eduardo