Best Fit Line and Slope for a Linear Regression Using Excel
To begin …..
1. Open up a new spreadsheet.
2. Input data into the A column that is your x-axis data, and label the top of the colum as "volume"
3. Input data into the B column that is your y-axis data., and label the top of the column as "mass"
Note: Adjust the decimal places for the column by choosing the column (click A or B),
open the FORMAT menu, CELLS, choose NUMBER tab,
select the NUMBER option, and change the decimal places box.
4. At the bottom of the A column, choose an open box and type in “slope =”
5. Highlight both columns of data, including the column labels.
6. Click the CHART tool (either in the toolbar or under the insert menu).
7. Highlight XY Scatter, and first subtype (no lines, points only).
8. Click NEXT.
9. Enter the chart titles and axis names in the next box.
10. Click Finish.
Mass vs. Volume
mass
0.00
4.20
6.33
8.72
12.60
15.00
Mass
volume
0.0
2.0
3.1
4.2
4.8
10.00
mass
5.00
0.00
0.0
1.0
2.0
slope =
3.0
4.0
5.0
6.0
Volume
Best Fit Line:
1. With the Chart Chosen (click on it), open the CHART menu.
2. Click on ADD TRENDLINE. If you don’t see it, click on the double arrows to expand the menu.
3. Choose LINEAR, and click OK.
Mass vs. Volume
14.00
12.00
10.00
Mass
8.00
mass
6.00
Linear (mass)
4.00
2.00
0.00
-2.00 0.0
2.0
4.0
Volume
To add the best fit equation, or equation for the trendline:
1. Right click on the trendline that you have created.
6.0
2. Select "format trendline" from the options.
3. Under the Options tab, select the "Display equation on Chart" option, and hit OK
Mass vs. Volume
14.00
12.00
y = 2.4305x - 0.484
10.00
Mass
8.00
mass
6.00
Linear (mass)
4.00
2.00
0.00
-2.00
0.0
2.0
4.0
6.0
Volume
Slope:
1. Choose the cell to the right of the word “slope =”
2. Open the INSERT menu, and choose FUNCTION.
3. Under the “Search for a function” option, type slope, and hit GO.
Now, under the “Select a function” option, select SLOPE.
4. A box opens up:
For the Known y’s, highlight the Mass data (only the numbers); for the Known x’s,
highlight the Volume data. Select OK, and the
slope will be automatically calculated and placed in the cell.
volume
0.0
2.0
3.1
4.2
4.8
slope =
mass
0.00
4.20
6.33
8.72
12.60
2.43
In Class Assignment:
Let's graph the Mass (g) versus Volume (cm3) for pre and post 1983 pennies,
apply a Best Fit Line, and determine the slope (density) of each:
Volume
2.0
4.0
5.5
7.0
9.0
Pre-1983 Mass
15.53
30.99
45.77
61.19
76.53
Post-1983 Mass
12.5
25.0
37.5
49.9
62.5