Frosh Research: How to Analyze Your Data

1. Show your results in a data table. TrialTime to travel 10.0 m, seconds (dependent variable) 1 st bearing (independent variable) 2 nd bearing (independent variable) 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 group Trial Time to travel 10.0 m, seconds (dependent variable) 1 st bearing (independent variable) 2 nd bearing (independent variable) Average 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) ENTER Do this for each of your groups.

What do you notice about the averages? Trial Time to travel 10.0 m, seconds (dependent variable) 1 st bearing (independent variable) 2 nd bearing (independent variable) Average Standard deviation They’re different, but how different? Does the 2 nd 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 (“1 st 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)

It looks like the 2 nd bearings a slightly faster than the 1 st 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