The Brief Case in Chapter 4 introduced the Cost of Living dataset that contains an estimate of the cost of living for 511 cities worldwide in 2017.
In addition to the overall Cost of Living Index are: the Rent Index, Groceries Index, Restaurant Index, and the Local Purchasing Power Index, which measures the relative purchasing power of buying goods and services in a city compared to the average wage in that city. Can we reconstruct the overall Cost of Living Index from the four component indices? Here is some multiple regression output:

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Assuming that the assumptions and conditions for this model are satisfied,
a) What might you recommend as a next step for developing a regression model? Why?
The researcher looking at this problem has proposed the following model:

b) What are the advantages of this model compared to the previous model with four predictors?
c) Why did the researcher remove the Rent Index from the model?
d) Do you think the model with three predictors is better? Explain briefly.v