I am fairly new at this. When plotting fairly simple XY scattergrams I have
noticed that when y decreases at an increasing rate, the Power trendline
Excel yields fits the data with a very high r-square. But when y decreases
at a decreasing rate, the resulting trendline fits poorly and the r-square is
low. How do I get the trendline (and resulting formula) to "invert" to
better fit the data? Thanks.

I suspect you have checked that the trend line option "Set intercept" =0,
forcing the trendline to go through (0,0). If so, uncheck, and even Excel
will figure out a better fit. (Right click trend line, Format Trendline and
go to Options).
HTH,
Henk

"agmoore" wrote:

I am fairly new at this. When plotting fairly simple XY scattergrams I have
noticed that when y decreases at an increasing rate, the Power trendline
Excel yields fits the data with a very high r-square. But when y decreases
at a decreasing rate, the resulting trendline fits poorly and the r-square is
low. How do I get the trendline (and resulting formula) to "invert" to
better fit the data? Thanks.