Confidence intervals in R Programming - Mini Project: Build & Apply

Confidence Intervals in R

📖 Scenario: You are a data analyst working with a small dataset of exam scores. You want to understand the range in which the true average score likely falls by calculating a confidence interval.

🎯 Goal: Build an R script that calculates a 95% confidence interval for the mean of a given numeric dataset.

📋 What You'll Learn

Create a numeric vector called scores with the exact values: 78, 85, 92, 88, 76, 95, 89

Create a variable called confidence_level and set it to 0.95

Calculate the 95% confidence interval for the mean of scores using the t.test() function and store the result in conf_interval

Print the confidence interval stored in conf_interval

💡 Why This Matters

🌍 Real World

Confidence intervals help us understand the range where the true average of a population likely lies based on sample data.

💼 Career

Data analysts and scientists use confidence intervals to make informed decisions and report uncertainty in their findings.

1

Create the data vector

Create a numeric vector called scores with these exact values: 78, 85, 92, 88, 76, 95, 89

R Programming

# Create the numeric vector scores with the given values
# Your code here

Need a hint?

Use the c() function to combine numbers into a vector.

2

Set the confidence level

Create a variable called confidence_level and set it to 0.95

R Programming

scores <- c(78, 85, 92, 88, 76, 95, 89)
# Create the confidence_level variable and set it to 0.95
# Your code here

Need a hint?

Just assign the number 0.95 to the variable confidence_level.

3

Calculate the confidence interval

Use the t.test() function with scores and conf.level = confidence_level to calculate the confidence interval. Store the result in a variable called conf_interval

R Programming

scores <- c(78, 85, 92, 88, 76, 95, 89)
confidence_level <- 0.95
# Calculate the confidence interval using t.test and store in conf_interval
# Your code here

Need a hint?

Use t.test(scores, conf.level = confidence_level) to get the confidence interval.

4

Print the confidence interval

Print the confidence interval stored in conf_interval by accessing its conf.int element

R Programming

scores <- c(78, 85, 92, 88, 76, 95, 89)
confidence_level <- 0.95
conf_interval <- t.test(scores, conf.level = confidence_level)
# Print the confidence interval
# Your code here

Need a hint?

Use print(conf_interval$conf.int) to show the confidence interval.