Frosh Research: How to Analyze Your Data

1. Show your results in a data table.Trial Time to travel 10.0 m, seconds

(dependent variable)

1st bearing (independent variable)

2nd bearing (independent variable)

1 2.59 2.152 2.46 2.463 2.46 2.654 2.68 2.095 2.56 36 2.18 2.597 2.76 2.258 2.86 3.349 2.23 2.5910 2.89 2.12

ONLY numbers go in the data cells, no letters

LABEL your quantities with appropriate units

LABEL the independent and dependent variables

2. Find the average for each groupTrial Time to travel 10.0 m, seconds

(dependent variable)1st bearing (independent

variable)2nd bearing

(independent variable)

1 2.59 2.15

2 2.46 2.46

3 2.46 2.65

4 2.68 2.09

5 2.56 3

6 2.18 2.59

7 2.76 2.25

8 2.86 3.34

9 2.23 2.59

10 2.89 2.12

Average 2.567 2.524

In the YELLOW cell, put =average(

Then select the cells with all the data for that group (all of the pink cells here), then close the parentheses

The yellow cell will look something like this:=average(B2:B11)

ENTERDo this for each of your groups.

What do you notice about the averages?Trial Time to travel 10.0 m, seconds

(dependent variable)1st bearing (independent

variable)2nd bearing

(independent variable)

1 2.59 2.15

2 2.46 2.46

3 2.46 2.65

4 2.68 2.09

5 2.56 3

6 2.18 2.59

7 2.76 2.25

8 2.86 3.34

9 2.23 2.59

10 2.89 2.12

Average 2.567 2.524

Standard deviation

0.241985

They’re different, but how different? Does the 2nd bearing really make the skateboard faster?

To find out, we need to include error bars.

Do this for each of your groups.

Put this in the GREEN box: =STDEV(

Then select the cells with all the data for that group (all of the pink cells here) – and CLOSE the parentheses

The cell will look like this: =STDEV(B2:B11)

3. Make a column graph, pt. 1• Insert, Column Graph • Set up a separate series for each group –– Right-click on the graph– “Select Data”– “Add” a series for each group• Name is the same as your first group (“1st bearing”)• Values - click on the cell that shows the average for

that group (“2.567”) • Repeat for each different group in your experiments

Here’s an example of how your graph will look now (after labels and titles are added)

10

0.5

1

1.5

2

2.5

3

Does changing the bearings affect the speed of a skateboard?

1ST BEARING2ND BEARING

Type of bearing

Tim

e to

trav

el 1

0 m

(sec

onds

)

• It looks like the 2nd bearings a slightly faster than the 1st bearings – but how can we know for sure?

• Margin of error! • Add in error bars: – Select a column on the graph– Chart, Layout, Error Bars, More options . . .– Custom– Select Values . . . select the STANDARD DEVIATION cell

for that group as the positive and negative values.

3. Make a column graph, pt. 2

Here’s how this graph would look now

10

0.5

1

1.5

2

2.5

3

Does changing the bearings affect the speed of a skateboard?

1ST BEARING2ND BEARING

Type of bearing

Tim

e to

trav

el 1

0 m

(sec

onds

)