## Question:

I have some data, see subset below. For each Method I want to calculate the difference in the mean Cq between the 2uL and 4 uL and the 4 uL and the 8uL.I have a function to calculate the mean for each Method, grouped by Volume. But I can’t figure out how to add another column with the difference. I think I might have to summarize the summ table, but I”m getting confused. Any help appreciated. Thanks

## Answer:

If the`mean`

delta should be for each ‘Method’, then create the column first grouped by ‘Method’ (or if it is based across all the `Method`

, then we do not need any grouping), get the `mean`

difference of ‘Cq’ where ‘Volume is ‘2ul’ and ‘4ul’ respectively, use that in grouping for calculating the rest of the summarised columnsIf you have better answer, please add a comment about this, thank you!