simple regression analysis issue

I am trying to get a simple regression analysis to work, using the \ operator, following the example in this page: https://www.mathworks.com/help/matlab/data_analysis/linear-regression.html

Somehow my regression coefficient is not coming up correct, it has an opposite slope and the value is off. Can someone help me figure out what I'm doing wrong?

Ultimately, I hope to run a loop and find the regression coeffecients between a column vector and a large number of other column vectors pulled from an array, but I need to first pass this simple test...

y = [-38.34; -42.48; -52.71; -49.72];
x = [69.482; 60.645; 37.093; 42.889];

b1 = x\y;
yreg = b1*x;

scatter(x,y)
hold on
plot(x,yreg)

Answer 1

[the cyclist]

The method you used does not include an intercept, so your fit is forced to go through the origin. Try this instead (which is also on that documentation page).

y = [-38.34; -42.48; -52.71; -49.72];
x = [69.482; 60.645; 37.093; 42.889];

X = [ones(size(x)), x]; 

b1 = X\y;
yreg = X*b1;

scatter(x,y)
hold on
plot(x,yreg)

[Coleman Hiett]

duhh! thanks for your help. I knew it would be something obvious that I wan't seeing...