how to curve fit

Hi coop Mac,

Is this what you are looking for? Click on the series, then Format Panel > Series > Trendline.

The best graph I find for this is the Scatter Plot.

Regards,

Ian.

Ian writes:

"The best graph I find for this is the Scatter Plot."

Agreed. The Scatter Plot is the only graph type in Numbers that plots y data against x data. All other types are Category graphs which plot y data for each category. Category graphs will produce an accurate trend line only for data where the categories represent evenly spaced data points (eg. totals per month or per week) If the x data is actual data, not evenly spaced, then the data points should not be evenly spaced along the x axis. Example below shows a scatter chart (Chart 1) and a Line chart (which is a category chart) constructed from the same data set. Y values for both are in column C, X values for the scatter chart are in column B. Category labels for the line chart are in column A, and are identical to the X values in column B.

Trend lines for both are the dark(er) blue line, specified in both cases as a second order polynomial.

Regards,

Barry

Hi Barry,

The Scatter Plot is the only graph type in Numbers that plots y data against x data

Plus the Bubble (X, Y, Z) graph in Numbers 3 😉

Regards,

Ian.

Hi coop Mac,

Thanks for the green tick and your feedback. Glad to help.

Not sure why this info was not in the "Numbers Help"?

Here is help for "chart"

Which takes you this webpage:

Regards,

Ian.