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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE General & Further Mathematics => Topic started by: black on November 03, 2011, 09:26:59 pm

Title: Linear regression on the CAS
Post by: black on November 03, 2011, 09:26:59 pm

quick question

what's the difference between using mx + b, and a + bx

i know that a+ bx is least squares regressions, but i ended up with the wrong equation for a trend line, when using a + bx, when asked for the equation of a least squares line for a set of data

thanks, and good luck to everyone tomorrow :)

Title: Re: Linear regression on the CAS
Post by: extcar on November 03, 2011, 09:30:33 pm

no difference i think, pretty sure a and m are both the gradient for the equation
did you check if the x axis started at 0?

Title: Re: Linear regression on the CAS
Post by: black on November 03, 2011, 09:45:04 pm

ahhh there we go, my bad

so if it starts at zero, we use mx + b? and a + bx for the others?

Title: Re: Linear regression on the CAS
Post by: extcar on November 03, 2011, 09:51:36 pm

it doesnt matter which equation you use,
but just know the one before 'x' is the gradient
so in mx+b, the gradient would be m
and in a+bx, the gradient would be b

i think you should just stick to one equation, but yeah they are the same thing, the b in both equations are different though and don't relate to each other