Make sure to include the unit of the values whenever appropriate.

Q1 Build a regression model to predict life expectancy using gdp per capita.

Hint: The variables are available in the gapminder data set from the gapminder package. Note that the data set and package both have the same name, gapminder.

library(tidyverse)
options(scipen=999)

data(gapminder, package="gapminder")
Life_lm <- lm(lifeExp ~ gdpPercap, 
                data = gapminder)

Q2 Is the coefficient of gdpPercap statistically significant at 5%?

Hint: Your answer must include a discussion on the p-value.

Yes it is statistically significant at 5% because the p-value is .0000000000000002 which is definitely lower than 5%.

Q3 Interpret the coefficient of gdpPercap.

Hint: Discuss both its sign and magnitude.

There is definitely an increase of .00075 years per an increase of 1 of gdpPerCAP.

Q4 Interpret the Intercept.

Hint: Provide a technical interpretation.

library(tidyverse)
options(scipen=999)

data(gapminder, package="gapminder")
Life_lm <- lm(lifeExp ~ gdpPercap + year, 
                data = gapminder)

Q5 Build another model that predicts life expectancy using gdpPercap, but also controls for another important variable, year.

Hint: This is a model with two explanatory variables. Insert another code chunk below.

library(tidyverse)
options(scipen=999)

data(gapminder, package="gapminder")
Life_lm <- lm(lifeExp ~ gdpPercap + year, 
                data = gapminder)

Q6 Which of the two models is better?

Hint: Discuss in terms of both residual standard error and reported adjusted R squared.

The residual standard error is better in the second one which means it misses by an average of 9.7 years compared to the 10.5 years on the first graph. The adjusted R square is better in the second one as well because the second graph explains 44 percent of the life expectance compared to only 34%

Q7 Interpret the coefficient of year.

Hint: Discuss both its sign and magnitude.

The life expectancy is .24 years when there are zero years which is not possible.

Q7.a Based on the second model, what is the predicted life expectancy for a country with gdpPercap of $40,000 a year in 1997.

Hint: We had this discussion in class while watching the video at DataCamp, Correlation and Regression in R. The video is titled as “Interpretation of Regression” in Chapter 4: Interpreting Regression Models.

The life expectancy is .24 years when there are zero years which is not possible.

Q8 Hide the messages, but display the code and its results on the webpage.

Hint: Use message, echo and results in the chunk options. Refer to the RMarkdown Reference Guide.

Q9 Display the title and your name correctly at the top of the webpage.

Q10 Use the correct slug.