x’ forecast only on HP-32E

[rawi]

Dave Britten wrote:

Quote:Couldn't you just find the minimum and maximum values of x for which the given value of y falls within a 95% confidence interval?

This would be possible if the x-variable had an distribution like the y-variable. But it has not. For instance x can be a time variable like a year. If there is an increasing trend a lower y would lead to a lower x, in this case to the beginning of the year. It easily can be that due to saisonality in the beginning of the year there is a higher y than in the middle of the year. So this does not make sense.