##The same researchers from the Population Council arecontinuing their investigation of the focal relationship betweenGDP per capita and fertility rates across countries. In order toconfirm the existence of the focal relationship, they decide tocontrol for countries’ population size. The researchers suspectthat larger populations could influence both GDP and birth rates(TFR) (but they hope this is not true, because it could invalidatethe focal relationship). The researchers conduct a multivariateregression by adding a measure of population size to the regressionequation presented in Equation 1 of Table 1. The results of thesecond regression equation are presented in Equation 2 of Table1.
Table 1. OLS Regression Coefficients RepresentingInfluence of Economic Output (GDP) and Control Variables on TotalFertility Rate
| Equation 1 | Equation 2 | Equation 3 |
Gross Domestic Product per Capita (x 1000) | -.033 (.000) | -.033 (.000) | -.007 (.141) |
Population size | | -.0000000784 (.378) | -.0000000773 (.063) |
Percentage of Women who can Read | | | -.043 (.000) |
| | | |
Y-intercept (Constant) | 3.36 | 3.39 | 6.47 |
| | | |
R2 | .207 | .213 | .657 |
(Significance level in parentheses)
The same researchers from the Population Council are continuingtheir investigation of the focal relationship between GDP percapita and fertility rates across countries. In order to confirmthe existence of the focal relationship, they decide to control forcountries’ population size. The researchers suspect that largerpopulations could influence both GDP and birth rates (TFR) (butthey hope this is not true, because it could invalidate the focalrelationship). The researchers conduct a multivariate regression byadding a measure of population size to the regression equationpresented in Equation 1 of Table 1. The results of the secondregression equation are presented in Equation 2 of Table 1.
In the box provided, explain why the researchers arecontrolling for population size. Specifically, whichelaboration strategy is being used? Or, what is the purpose ofadding this new variable (population size) to the equation? You maydraw a picture on your worksheet. You should not reference anynumbers from the equation in your answer to this question.
Table 1. OLS Regression Coefficients RepresentingInfluence of Economic Output (GDP) and Control Variables on TotalFertility Rate
| Equation 1 | Equation 2 | Equation 3 |
Gross Domestic Product per Capita (x 1000) | -.033 (.000) | -.033 (.000) | -.007 (.141) |
Population size | | -.0000000784 (.378) | -.0000000773 (.063) |
Percentage of Women who can Read | | | -.043 (.000) |
| | | |
Y-intercept (Constant) | 3.36 | 3.39 | 6.47 |
| | | |
R2 | .207 | .213 | .657 |
(Significance level in parentheses)
Question 1 What conclusion should theresearcher draw about the focal relationship between GDP per capitaand birth rates when comparing Equation 2 to Equation 1? You shouldclearly referencing the specific numbers that you are using to drawyour conclusion.
