# Data Analysis Tool

As I’ve taught physics using the Modeling Instruction philosophy, we collect quite a few data sets about physical relationships that need to be analyzed.  I’ve tried a few ways for students to graph data:

Method Pros Cons
Graph Paper * Requires a firm grasp of scales, slope, and y-intercept
* Students gain a better grasp of the meaning of these quantities and where they come from
* Flexible — few limitations
* No technology quirks to learn
* Time-consuming
* Requires multiple iterations to linearize non-linear relationships
* Difficult to test several analysis methods to determine the best fit
* Best-fit lines, slopes, and y-intercepts are not as accurate
TI-84 Calculator * Can be used on the AP Exam!
* Manual window-setting requires students to consider how they will view their data
* Students can create their own best-fit line by writing a linear equation in Y1
* OR, it has LinReg capabilities
* A bit quicker than graphing by hand
* Data entry, turning stat-plots on, and graphing is not as intuitive as it should be
* Regressions are also not very intuitive, and getting the linear fit to display on the graph is another hurdle
* Doesn’t handle units at all — that’s up to the student
* No easy way to get a printout of the graph for inclusion in reports
* Not all of my students have this calculator
Vernier LoggerPro * Quick
* Takes care of units, labels, and titles
* Easily adjust what is graphed on each axis
* Support for force, motion, and other sensors
* Linear fit is available with 1 button click
* Supports graphing multiple data sets, a secondary y-axis scale, and many advanced features
* Linearizing with calculated columns is somewhat cumbersome; requires quite a few steps
* For novices, the large number of features make it difficult to remember the correct steps to get the desired results
* Not likely to use this software in other contexts
* Not widely available (though the site license is generous)
Microsoft Excel (or Google Sheets) * Powerful and flexible
* Supports graphing multiple data sets, secondary y-axis scale, and many advanced features
* Likely to be used in college, industry, etc.
* Widely available (and for Google Sheets, free)
* Need to set up own data table
* New versions of Excel do not label axes by default
* Google Sheets graphs lack some features and are not the most intuitive (though I haven’t used them in a couple years so perhaps they’ve improved)
* Again, the huge number of features often make it hard to find the desired functions

To start the year, I always have students graph data using graph paper for a couple weeks.  I think students need to be able to do it themselves and understand the basic considerations of choosing scales, deciding what to plot where, and finding slopes and y-intercepts manually before having a device/computer do it for them.

In the past, after students got more comfortable graphing things by hand, I showed them how to use some tools (in the past, this tool has been LoggerPro).  But, after having to guide students through the LoggerPro linearization process time and time again for each lab, I wanted to find a better solution.

I ended up writing a quick online data analysis tool (using the graphing capabilities of CanvasJS).  Check it out here.  It does most of what I need it to, which is to take a set of data, graph it, allow students to linearize it (graph y vs. x2, y vs. 1/x, etc.), and output the best-fit line equation.

Improvements I may try to implement in the future:

• CanvasJS does not allow formatted text on axis labels (so squared, cubed, etc. is displayed as ^2 and ^3) – Find a workaround?mostly solved – it does allow Unicode characters!
• Data input improvements (arrow keys for navigating)implemented though still has some quirks
• Allow graphing of two (or more) data sets at once