- #1

KThy

- 2

- 0

I have a set of records with the following data for each record: interval, mean speed, standard deviation of speed, number of observations. Exempli gratia:

Code:

```
1, 77.2, 1.75, 10
2, 75.9, 2.05, 12
```

Now, if I want to aggregate the data to get mean speed and standard deviation over two or more intervals (1 and 2 above), calculating the weighted mean is no problem but how - if possible - do I calculate the standard deviation for the aggregated intervals?