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## How to get a regression curve for an x-y value pair where a single x can have multiple y values in the set?

I am trying to generate a regression curve for a set of x-y values where a single x value can have multiple y values. Although in the end, only one y value should be the correct one and rest all should be categorized as outliers. Is least square linear regression the right way to do this? I was reading a paper which said I could apply linear regression here; but when I use an existing code library and input my data, it gives an error. How do I get the line for this data?

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It is a normal situation that doesn't make a difference to the analysis. The software shouldn't complain, except perhaps if you give it degenerate case like all $x$ values equal. – Brendan McKay Oct 18 at 11:44
This question really belongs here... stats.stackexchange.com/?as=1 – Kjetil B Halvorsen Oct 18 at 14:58