Data Analysis Using the TI-83/84

The data gathered in experiments would be useless without some way of organizing and analyzing the information. The TI-8x series of calculators have automated this process. You will be able to calculate means and median, graph the information, use regressions (best fit line) to predict data points, and do basic statistical tests on data sets.

Entering Data

1.         Determine your independent and dependent variables. The independent variable will be entered into list 1 and the dependent variable into list 2.

2.         Use “CLRLIST L1, L2" to clear the lists.

3.         Push the “STAT” key.

4.         Select “EDIT” from the menu. This will bring up the list editor. You will be entering data into L1 (independent variable) and L2 (dependent variable). You will have the same number of entries in each list.

5.         Enter the data using any format for the number. Press “ENTER”. Your calculator with store the data in the list in the format you select in “MODE”.

6.         Continue entering data until you have entered all data. Note: L1 and L2 must have the same number of data points.

Graphing the Data

1.         Push the “2^nd” key and the “Y=” key to access the STATSPLOT menu. Select PLOT1 on the menu.

2.         On the first line select “ON”.

3.         On the second line select the first graph, a scatter plot.

4.         Set your XLIST to L1 and your YLIST to L2.

5.         Select any of the three marks for your data points.

6.         You must now set the window. Push the “WINDOW” key.

7.         Set XMIN to 20% below your lowest data point. Set XMAX to 20% above your highest data point. Set XSCL to 50.

8.         Set YMIN to 20% below your lowest data point. Set YMAX to 20% above your hiest data point. Set YSCL to 50.

9.         Press “GRAPH” to see a plot of the data.

Drawing the Best Fit Line

1.         Press “STAT” and select CALC on the menu.

2.         Based on the same of the points on your plot select the regression that best seems to fit the data. Generally use LINREG if point approximate a straight line and PWRREG for those that appear to form a curved line. If neither of these lines fit experiment with other regressions.

3.         Press “ENTER” twice. The calculator will display the regression vaiables.

4.         You must now enter the REGEQ into Y=. Push”Y=”. Push “VARS” and select “STATISTICS” from the menu. Move the cursor to EQ and push “ENTER” to move the REGEQ to Y=.

5.         Push “GRAPH”.

Using the Best Fit Line

1.         With the graph displayed push “TRACE”.

2.         Using the up-arrow select the best fit line to trace. You will see the equation in the upper left corner.

3.         Enter a value for the independent variable. You should see that in the lower left corner (X=#####). Push “ENTER”, the value of the dependent variable will be displayed in the lower right corner (Y=#####).

Using the Table

1.         Once you have entered REGEQ into Y= you may use the table rather than the graph to find new values for dependent variables.

2.         Push “2^nd TBLSET”. Set TBLSTART to zero. Set DTBL to 1. Set “INDPNT” to ASK. Set DEPEND to AUTO.

3.         Push “2^nd TABLE”. If necessary, use “DEL” independent variables from the table. Enter a value for the independent variable and press “ENTER”. The dependent variable will be in the Y column.