I have sort of data consist of two variables --dependent and independent-- and want to fit it in linear-plateau form. How to do that in excel or other software and how to identify the inflection point?
I don't use Excel for statistics, but it's difficult for me to imagine fitting a linear plateau model in Excel.
It's relatively easy to do in R or SAS.
For R, you might see the example of linear-plateau here ( https://rcompanion.org/handbook/I_11.html ) (with the caveat that I am the author of this page). You can run R without installing it here ( https://rdrr.io/snippets/ ), although if you are doing analyses at this level, you would likely benefit from getting access and familiarity with statistical software like R or SAS.
You need to install the Solver add-in, then (typically) set up a column of observed values, and a column of calculated values based on the values of Coefficients in separate cells. Use the columns of observed and calculated values to calculate residuals, then a sum-of-squares of these residuals. This is the cell you want to minimise using the Solver, by varying the values of the Coefficient cells.
You might need to enable macros.
Hello Ali,
in EHello Ali
Hello Ali
in Excel, you should your data represent in an x-y coordinate system.
If you have done it, go into the graphic and click on "Add trendline".
Please chooses "Polynomial". Choose second order for maximum respectively plateau.
Choose the third order for the inflection point.
Then go to "Options" set a hook on "Display equation on chart",
set a hook on "Display R-squared value on the chart".
To find the exact points of maximum respectively inflection point please derive the functions.
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