Hello,

Hopefully I can describe what I am trying to do, as I cant quite figure it out myself.

I have a table with a list of dates and quantities.

1/1/2011, 3
2/1/2011, 6
2/1/2011, 2
3/1/2011, 1
4/1/2011, 2
4/1/2011, 3
4/1/2011, 6

(yes there could be multiple entries for a given day).

I have another table displaying various data caluclated from this table, on a day by day basis. For example, I am using SUMIF to display the total per day, AVERAGEIF to display the daily average over the last x days.

What I am now trying to do is use LINEST to display a forecast for the next day, based on the previous x days totals.

Could anyone help me? I know I could use LINEST against the values in my summary table based on my SUMIF results, but I want to have all data calculated directly from the source data table, and not make calculations on my other calculations.

I hope this makes sense.

Many thanks,
Ben