The average number of people in a family that received welfare for various years is given in table.
year welfare family size
1969 4.0
1973 3.6
1975 3.2
1979 3.0
1983 3.0
1988 3.0
1991 2.9
a. using “year” as the independent variable and “welfare family size” as the dependent variable, draw a scatter plot of the data.
b. calculate the least-squares line. put the equation in the form of: y = a + bx
c. find the correlation coefficient. is it significant?
d. pick two years between 1969 and 1991 and find the estimated welfare family sizes.
e. based on the data in table 12.29, is there a linear relationship between the year and the average number of people in a welfare family?
f. using the least-squares line, estimate the welfare family sizes for 1960 and 1995. does the least-squares line give an accurate estimate for those years? explain why or why not.
g. are there any outliers in the data?
h. what is the estimated average welfare family size for 1986? does the least squares line give an accurate estimate for that year? explain why or why not.
i. what is the slope of the least squares (best-fit) line? interpret the slope.