If you change your chart type from line to scatter, you can add the qurterly
series with its own x values. If you want the line to be a step fuction, you
will need two points for eac querter (one for the first day and one for the
last). You might also be able to do the same with line charts with date
category axis but I have not tried...
Best wishes, Boris

"Mike" wrote:

Hi. I have a line chart with a series of percentages in N14 through N65.
There is one point for each week of 52 weeks of the year.

In cell N7 I have the running average for Q1.
In cell N8 I have the running average for Q2.
In Cell N9 I have the running average for Q3.
In Cell N10 I have the running avergage for Q4.

I would like to chart another line that shows the quarterly average. 13
values of N7, followed by 13 values of N8; then N9, then N10.

Is there a way to do this other than adding another column that contains
these values?

Thanks,
Mike.