Description of the data, data_quiz5

library(tidyverse)
library(scales)

Q1 Import data

data_quiz5 <- read.csv("data_quiz5.csv")

Hint: The data is posted in Moodle. Look for data_quiz5.csv under the Data Files section.

Q2 Review data

head(data_quiz5)
##     country continent lifeExp      pop gdpPercap
## 1   Albania    Europe  76.423  3600523  5937.030
## 2   Algeria    Africa  72.301 33333216  6223.367
## 3 Argentina  Americas  75.320 40301927 12779.380
## 4 Australia   Oceania  81.235 20434176 34435.367
## 5   Austria    Europe  79.829  8199783 36126.493
## 6   Bahrain      Asia  75.635   708573 29796.048

Hint: Use head() to display the first six rows.

Q3 Visualize data

library(ggplot2)
data(data_quiz5)

ggplot(data_quiz5,
     aes(x = gdpPercap,
         y = lifeExp)) +
  geom_point()

Hint: Create a scatter plot to examine the relationship between GDP per capita (mapped to y-axis) and life expectancy (mapped to x-axis).

Q4 Build a regression model to predict GDP per capita using life expectancy.

houses_lm <- lm(gdpPercap ~ lifeExp,
                data = data_quiz5)
summary(houses_lm)
## 
## Call:
## lm(formula = gdpPercap ~ lifeExp, data = data_quiz5)
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -17319.8  -4512.4    -63.2   3443.1  24014.4 
## 
## Coefficients:
##              Estimate Std. Error t value Pr(>|t|)    
## (Intercept) -215340.5    18057.2  -11.93   <2e-16 ***
## lifeExp        3075.6      237.6   12.94   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 7578 on 81 degrees of freedom
## Multiple R-squared:  0.6741, Adjusted R-squared:  0.6701 
## F-statistic: 167.5 on 1 and 81 DF,  p-value: < 2.2e-16

Q5 Is the coefficient of life expectancy statistically significant at 5%?

The P-Value for the variable is less than the value of 5% meaning it is statistically significant.

Q6 Interpret the coefficient of life expectancy.

The coefficiency of life expectancy has a p-value of -2.2e-16 saying it does have statistical significance at 5%

Hint: Discuss both its sign and magnitude.

Q7 Your friend suggests that the more populous a country, the higher its standard living (GDP per capita) is. Create a new model below by adding an additional predictor to the regression model above to test this hypothesis. Is the new variable statistically significant? What would you say to your friend regarding his/her claim?

library(ggplot2)
data(data_quiz5)

ggplot(data_quiz5,
       aes(x = pop,
           y = gdpPercap)) +
  geom_point()

This is still statistically significant because the p values are not above 5 percent.

Hint: Make your argument using the relevant test results, such as p-value.

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

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

Q10 Use the correct slug.