Stats test PART 2
refer to graph on paper to check yes, linear
Draw a scatterplot of the data. Let 1960 be year 1 and 2010 be year 50. Does there appear to be a linear relationship in the data?
equation: CO2= 311.59 + 1.47(50) (2015 is 50 years from 1960; x=50) CO2 = 385.09 Residual = obs - predicted Residual = 389.78 - 385.09 = 4.67 Residual = 4.67
Find the residual for 2010.
1) find slope (b) Slope=y/x Slope = CO2 levels in ppm / years 2) increase of (b) 1.47 CO2 levels in ppm/year
Interpret the slope of the regression line, in terms of CO2 concentrations.
11
Levels of carbon dioxide (CO2) in the atmosphere are rising, far above any levels ever before recorded. Levels were around 278 ppm in 1800, before the Industrial Age, and had never in the hundreds of thousands of years before that gone above 300 ppm. Levels are now over 400 ppm. Table shows the rise of CO2 concentrations over the last 50 years from 1960-2010. We can use this information to predict CO2 levels in different years.
1) stat 2) edit 3) enter data 4) stat 5) calc. 6) 4 7) enter 8) answer: r=____
Steps to calculate r (correlation coefficient)
1) know form: y=a+bx 2) y= response variable (with curved line above) 3) x= explanatory variable (with curved line above) 4) stat -> calc. -> 8 -> enter a=______ b=______
Steps to calculate the regression line (least squares line) USING TECHNOLOGY
r=0.993 yes
Use technology to find the correlation coefficent between years and CO2 levels. r=__________. Does this value support your answer in part b?
y = a + bx _______ _______ CO2 = 322.59 + 1.47 x year
Use technology, calculate the regression line to predict the CO2 levels from a given year: y=
y = a + bx x=60 CO2 = 311. 147 (60) CO2 = 399.79 Co2/ppm
Use the regression line to predict the CO2 level in 2020.
year
What is the explanatory variable (x-axis)?
CO2 concentration (in parts per million)
What is the response variable?
311.59 stat -> calc -> 8 -> enter yes
What is the y=intercept of the line? Does this make any sense in the context of this problem?
