Regression Analysis

[#1]

Hello Everyne. 

One new question: I have a regression line (please see attachment)  Y xs X. 

I have calculated the confidence intervals for Y as a function or X. 

However based on this fit, when I want to get the confidence intervals of X how do I calculate them. 

The reason for this question is that ofter times we obsere a response (Y) and then read back the X value from the regression line. Therefore when an X value is read out of this regression line, it should theoretically also have a confidence interval ? 

I am much obliged for your kind assistance. 

[#2]

You can get the confidence interval for your X variable by running the Distribution Platform.

See Mark's response below

[#3]

Hi there, 

You mean distribution  X as Y   (right) ?

But this is not very helpful, it generates no meaningful report.  I would be obliged for your assistance . 

[#4 · Accepted solution]

This is known as inverse prediction or the calibration problem. You have a standard curve and correctly fit Y (response) versus X (known levels). This result is available but not in the Bivariate platform that you used. Use the Fit Least Squares platform instead. Select Analyze > Fit Model. Enter your Y column in the Y role, enter your X column as an Effect, and click Run. Click the red triangle at the top and select Estimates > Inverse Prediction. Choose your confidence level and your desired type of interval. Enter up to eight Y values. Finally, use the option at the bottom to indicate if you want an interval estimate for the mean X (default) or the individual X value (check the box).

[#5]

This result is available but not in the Bivariate platform that you used.

Use the Fit Least Squares platform instead.

Sorry, could not find this platform ?

[#6]

The platform that Mark is referring to is:

     Analyze==>Fit Model

Within it you can choose the Least Squares