Plotting a line which would include 95% of points above and below the regression line

Hello,

I have used the segmented regression method to plot linear lines over my scatter plot. Now I want to draw a line parallel to the segmented regression line, both above and below (+ & -), which would include approximately 90-95% of the points.

Can anybody help me with this? thank you

Answer 1

[Ahmet Cecen]

Find your residual vector.

Use prctile() on the residual vector to find the points at your upper and lower bounds.

Solve the equation BoundY = Slope*BoundX + Location, for Location.

Plot the lines with both the upper and lower bound Locations.

[Tushar Agarwal]

@Ahmet Thank you for your response, but i dont seem to understand where i can find the residuals, as I have done a piecewise regression - so could you help me a bit more? :D I am fairly new with this.

[Ahmet Cecen]

Well you in the end, you should have a function as a result of your regression in the form:

Yestimate = f(variables);

Residuals are simply:

Yactual - Ytraining

Then you can find the value at which the residuals are bigger than a certain value using prctile(Residuals,percentilevalue).

Now you can find the index of the yactual at which you observe that residual, then plot a line through it to achieve the desired effect.

[Tushar Agarwal]

Thankyou I was able to solve this.