 Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.

# st: Accumulated mean and standard deviation

 From Pedro Nakashima To statalist@hsphsun2.harvard.edu Subject st: Accumulated mean and standard deviation Date Sun, 8 Jan 2012 13:50:07 -0200

```Hi everybody

I need to replicate the following data:

clear*

input x mean sd
2 2 .
4 3 1.4142
1 2.33 1.5275
3 2.55 1.2909
end

The variables mean and sd are like a mix of sum() and egen functions.

For the variable "mean", in each observation j, its entry is the mean
of the values of the variable "x" from observation 1 up to observation
j.
For example:
2 is the mean of 2
3 is the mean of 4 and 2
2.33 is the mean of 1, 4 and 2
2.55 is the mean of 3, 1, 4 and 2

The same is true for the variable sd, but here we consider the
standard deviation.

Does anyone know how to solve this problem?

Many thanks,
Pedro Nakashima.
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/
```