looking over a scatter plot, how does one find the best fit line?

Question

give example if possible and show standard equation form

Answer 1

depending on the level of math, you either use statistical sampling methods or draw a line through the scatter with an equal number of points both above and below.

Answer 2

If drawn by hand:
1) if when x=0, y=0, then make sure you cross that point
2) with a ruler, draw a straight line with 1/2 the dots above the line & 1/2 below it
3) m = slope = rise / run = change in y / change in x
4) pick any point to use as a reference (x,y)
5) y = mx+b ==> use algebra to find b

If you're in MS Excel:
1) list #s in columns x & y (e.g. columns A and B)
2) highlight the #s, then click the button that looks like a bar graph (on the top of the screen)
3) follow instructions to get your scatter plot
4) right click one of the dots, and choose "Add Trendline" *****
5) choose the type of fit ("Trend/Regression type") you want to try
6) click the "Options" tab
7) check "Display equation on chart" and "Display R-squared value on chart"
8) keep the fit line with the R-squared value closest to 1

Answer 3

This can be done using Excel.
It's quite easy, and Excel will give you the slope, x and y intercepts also.

Makes graphs for homework really professional looking!

Answer 4

Take the data points and calculate the least squares data and coeffcients.