If I have two sets of data points, for instance:

1 10

2 14

3 17

4 12

5 19

and

1 10

2 14

3 17

4 12

100 112

The linear regression is bad for the first set and good for the second, if you look at R^2, but it is still a bad line. I was told that standard deviation of the slope can help me, since for the second data set there is seemingly more leeway, thus the first 4 points become less represented by the regression. However, this is not the case.

I would like to ask whether there is a parameter or a statistical analysis of the data set that can give me evaluation of the quality of regression.

I do see a picture of residuals, however I am sure there is something more that can help me...

Thank you very much in advance,

Alex.