NAME(S): ____________
JongJin Lee
______________________________________________Correlation Study
Select two variables (related or unrelated), and collect the data. Analyze the data to determine if there is a correlation. Fill out the questions below, and graph your data. Draw the line of regression.
1) Variable 1 (or independent variable): _ height (cm)_________
Variable 2 (or dependent variable): ___circumference of wrist (cm)________
*Be consistent when collecting your data. Define the rules for data collection methods first*
2) Collect PRIMARY data. Use the STAT PLOT feature to graph the points. Use the STAT CALC menu and select LinReg(ax+b). Record the points and line of regression on the graph.
Or, create a scatter-plot on a spreadsheet. Label both axis, and provide a title for the graph.
I chose two variables from the census at school data. I chose students’ height and the circumference of students’ wrist to see wether there are correlation between them. The two data have strong correlation, even though it has an outlier of (198,184).
If the outlier has been taken out from the graph, it will have more strong correlation. It has r value of 0.726 and the linear regression equation is y= 1.50X + -95.73. But it will changed to 0.744 of r value and the linear regression equation become y= 1.79X -145.82
height wrist
178 150
176 163
170 145
166 150
185 180
179 152
179 170
177 180
177 189
178 159
174 180
176 160
168 150
165 160
160 140
178 180
171 150
175 180
160 150
198 184
174 185
180 178
178 190
177 170
182 185
169 150
154 120
3) What is the r-value? r = _0.726_; What does this mean? it is a strong positive linear correlation 4) What is the Linear Regression Equation? ___y= 1.50X + -95.73__________________
5) What were the potential extraneous (external) variables? How could you control these?
Students may not have taken accurate measurements. We could have one person measure everybody.
