Regression – Calculator Lab #3 – TI30X-IIS

[Pages:1]Regression ? Calculator Lab #3 ? TI30X-IIS

Data entry directions for the TI30X- IIs

1) Turn your calculator on and hit 2nd then DATA. Cursor to the left using the left arrow key until you come to the CLRDATA option, then hit ENTER.

2) Hit 2nd STAT, cursor to the right using the right arrow key until you come to the 2-VAR option. Hit ENTER.

3) Now you're ready to begin entering the data. This is bivariate data so you'll be entering an x value and its corresponding y value for each data point. Since we've chosen nicotine to be the dependent variable these values will be entered as the y's. Values for Tar will be the x's. Hit the DATA key. Then enter the first value for TAR ? this is 16 ? and then hit the down arrow . This sets the calculator up to accept the y-value that corresponds to the first entry. This is 1.2.

4) Hit the down arrow again to prepare for the next pair of values. Continue this procedure until all 29 points have been entered.

5) To get the correlation coefficient hit STATVAR then move the cursor to the right using the right arrow key until you come to "r". The displayed value is the sample correlation coefficient. Use this output to answer question E above.

6) Verify that this agrees with your visual classification of the strength of the relationship between tar and nicotine. In other words, if you thought that the correlation was strong, the r value should be close to 0.9 if you thought it was weak then the correlation coefficient should be less than 0.6.

7) The linear model that we're estimating is: y = ax + b. Where "a" represents the slope and "b" represents the y-intercept. Note that this is different than the model we're using in class. To get these values move the cursor with the left arrow key until the cursor rests under the estimator of interest. Use the results from this step to answer question F above.

8) To estimate a "y" value given an "x" value move the cursor to the right until it rests under y'. Then hit enter. This prepares the calculator to accept an entry for "x". Enter 10.5 then close the parentheses and hit enter. The number displayed is the y-value given an x-value of 10.5. You can use this result to answer question G above.

Rick Gumina

STCC201 Page 1 of 1

TI30X-IIS_Regression-calculator_lab3.doc

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