I want to make a nonlinear regression of the isotherm adsorption using Langmuir model but unfortunately when i introduced my data i have alaways the same message " There are no replicates. Minitab cannot do the lack of fit test based on pure error". What shall i do ?
You can find the nonlinear regression model in MINITAB in the link below.
https://blog.minitab.com/blog/minitab-statistical-softwares-nonlinear-regression-tool#:~:text=Chemists%2C%20engineers%2C%20scientists%20and%20others,relationships%20and%20make%20sound%20predictions.
When you say "when introduce your data", when stage do u exactly mean? Import the data, or u entered the data manually already then it is the stage where you are identifying your response variable and specifying your mathematical expression in the Expectation Function dialogue box? Please provide more information, including your variables and their measurement levels - perhaps a snapshot of your mathematical expression can do. Thanks
If the above suggestions don't work take more data with some repeats.to see why look at a plot of the Langmuir isotherm function. Best, David Booth
PS PLEASE look at the lack of fit test. It is ALWAYS based on repeats. Good heavens take a regression course, please. Or look at : https://www.google.com/search?client=firefox-b-1-d&q=f+test+for+goodness+of+fit
David Booth
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwinu9aShdDuAhXSqHEKHehwBgsQFjAPegQIHhAC&url=https%3A%2F%2Fsubscription.packtpub.com%2Fbook%2Fbig_data_and_business_intelligence%2F9781782170921%2F5%2Fch05lvl1sec74%2Ffitting-a-nonlinear-regression&usg=AOvVaw19gogEpYLP4QfuJcDWUE9I
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