plotting certain x points from a large data group

[znova]

Is there a function or method to plot say every 8th point in the x data (time
stamp) column with many other columns of data that is to be plotted to the y
axis per the x (time stamp) data points..

 

[Pete_UK]

You can extract every 8th cell into a different (contiguous) range,
and use that secondary range as the data source for your graph. If
your data is in column A starting with A2 (allowing for headers), and
you want to get A2, A10, A18 etc in sucessive cells in column D, then
put this in D2:

=INDEX(A:A,(ROW(A1)-1)*8+2)

then copy down as required. You can have a similar formula in column E
(say) for your Y-values.

Hope this helps.

Pete