2
$\begingroup$

I'm new to statistics and I ran into this question, what I know is $Y=A + BX$ but in the question the value of $B$ is negative, is it normal for the $B$ value to be negative?

Here is the question, you don't have to answer it, I just added as a reference.

Estimate the value of $Y$ when $X = 30$ for the following regression equation: $Y = 6.2 - 1.4 X$.

$\endgroup$
7
$\begingroup$

$B = -1.4$ for you: $Y = 6.2 + (-1.4)X$. What this means is that same as if it were $+1.4$: that for every one-unit change in $X$, there is a $B$-unit change in $Y$. In this particular case, the change is that, for every one-unit change in $X$, $Y$ decreases by $1.4$ units.

$B<0$ is certainly acceptable. Consider a relationship like expected snowfall tomorrow as $Y$ and today's temperature as $X$.

$\endgroup$
  • $\begingroup$ Your snowfall-temperature example is wrong, apart from that relation being very nonlinear, consider temperature $-15^\circ\text{C}$, there will not be snowing. Increase temperature with 10 degrees, expected snowfall will increase! $\endgroup$ – kjetil b halvorsen Jul 30 '20 at 0:44
0
$\begingroup$

Yes you can have negative weights. The simplest example of when this would happen is when you have a factor that has a negative correlation to the output Y. This would imply for every X unit increase, there should be a corresponding B * X decrease in Y. In your example, for every unit increase of X, Y should decrease by a factor of 1.4

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.