Hi Colin,

I'm assuming that you are using an XYscatter chart with your data,
let's say five years worth in say A1:B2000 or whatever.

Apply your trendline to all the data and format it to be say, blue.
Then right click on the chart goto Source data and add series.

Add a new series for each set of data at yearly intervals. Each
series accessing only the data from that year.
So that you will have five new series.

Now do the same for quarterly intervals so that you will have another
20 series.

Now apply a trendline to each of your yearly series and format them
to be say yellow.

Repeat the process for each of your Quarterly series and format
them to be red.

Hide each yearly and quarterly series so that all that is left on the
chart are the trendlines.

You should be left with a chart showing all of your data points
and three separate different colored trendlines showing quarterly
trends, yearly trends and five yearly trends.

HTH
Martin


"Colin Foster" wrote in message
...
Hi All,

I can add lots of different trend lines to my Excel charts... except
one...
I need to reflect seasonal fluctuations, so that whilst during the summer
months work levels tend to fall, the overall trend of the business is
increasing & I'd like to see a trend line showing the future expected
growth,
but which still shows a drop-off during the summer.

Is this possible with a trend line, or do I need to use a function to
create
the trend figures & then chart them?

Thanks in advance for your help

Regards
Colin Foster