what am i doing wrong?

Topic

New Reply

hello everyone;

i have a simple table in excel (office 2003), and am interested to extrapolate to (let’s say, year 2020) using the equation of the linear trendline.
if i select to plot line with dotted points (top graph), i get one trendline equation, but if i select to plot from XY scatter, i get another trendline equation !!!!!
both plots of data are similar (seem rather identical), in pattern, however the difference?

any help?

TIA.

daniel rozenberg

Reply | Quote

Replies

Daniel,

If you use a linear trendline, the mathematical equations used to plot that line are only accurate for that line which may or may not approximate the scatter plot. There are lots of trendlines with varying mathematical approximations, so maybe you need to select a different trendline till you find one that looks close to the scatter plot. That will give you equations that more closely match each other.

I’ve attached a chart that shows the plot of some temperature data over time that has a 4th order power trendline added. Their equations won’t be close at all, but a averaging trendline will more closely match that of the scatter plot.

Reply | Quote

This is discusses in more detail in the threadhttp://lounge.windowssecrets.com/index.php?showtopic=778704

Steve

Reply | Quote