Math's paper 2 accuracy - line of best fit

Incompetent

I was just doing some paper twos, and generally when I do the correlation questions the line of best fit and the answers I get from using it are always off by a good bit. When they're marking will they take the time to check and see if mine is correct, or will they go by the marking scheme?
For example just there I got a slope of 2.33 (which is correct for my line), when the answer is given as 3.

I understand everyone will have a different answer, but how will they mark it?

finality

They give a range, I'm pretty sure. Do you have a roughly equal number of points on either side of your line? If you're not waaay off you'll be fine.

DepoProvera

My teacher says to get the slope of the actual line of best fit on your calculator and just draw your line roughly based on that.

SureYWouldntYa

to properly draw line of best fit, its best to get the mean of the 2 sets of data, of the the 2 variables. the line of best fit will go through the mean and helps you to get it more accurate

MathsManiac

If the number of data points is small, you could use your calculator to get the exact line. (Input the data the same way as for a correlation coefficient, and then just press the buttons that give the slope and intercept.)

I'm sure a reasonable tolerance will be allowed anyway.

For example, when they trialled the sample paper in the pilot schools, the report says (on page 31) that they used the following in the case of Question 7:

(iv) Scale 5A
Accept:
Line whose slope is between 1·5 and 5, (i.e. rises by at least three and no more than ten grid squares across the full width of the diagram) and has at least four data points on either side.

DepoProvera

Yeah my mock's marking scheme gave values and said (or two accurately read points from student's scatterplot)