basically I want to write y = averagevalue

"Gaijintendo" wrote:

I was adding an average line like this

Series 1 Series 2
10 average(series1)=25
20 25
30 25
40 25

and plotting the average line.

I then tried plotting a linear trendline, with the 'set intercept' set to
the average (25). However the lines were not always perfectly horizontal (I
can't understand why).

Is there a way to create an average line?