Can anyone help me with a regression line equation?

Question

I have created a scatterplot with a regression line using excel, and the equation excel has given me for the line is:

y = 0.8734x - 4.1304

But this doesn't seem to fit the y=a + bx format? or does it? Shouldn't it be y = -4.1304 + 0.8734x? or does that mean the same thing?

Another thing I don't understand is that my graph shows a positive relationship between y and x (as x goes up y goes up) yet the equation seems to show a negative relationship, or am I totally off track?

Any help would be much, much appreciated!

Cheers

Josh.

Answer 1

your equation is fine.  0.8734 is your slope and -4.1204 is your intercept.  Think in this way rather than in constants a and b.  multiply the slopy by the independent variable and adjust for the intercept to find the dependent variable.

As the independent variable increases, the dependent variable increases; however, dependent variables may be negative.  The slope may start in the fourth quadrant but gradually slope upward, as long as the independent variable is positive.

Answer 2

yes that is the same thing. the equation shows a negative relationship (because the term with the x in is positive)

Answer 3

what you have is fine.

you have y = 0.8734x - 4.1304

that's the same as...

y = -4.1304 + 0.8734x

y =     a      +     bx

a = -4.1304 and b = 0.8734

Answer 4

Solution is correct:

b= 0.8734

a= - 4.1304

On this equation it is a positive relationship between x and y

Answer 5

I doesn't matter how you write it.  a=-4.1304, b=0.8734

When x increases y increases.  x=0, y=-4.1304

x=1, y=-3.257