R Programming Language Certification Statistical Analysis & Modeling in R 2

Question 1

Which R function fits a logistic regression model?

Accepted Answer

glm() with family = binomial

Answer

Logistic regression is fit with glm(y ~ x, family = binomial(link='logit')), which models binary outcomes.

Question 2

What does the confint() function return for a fitted model in R?

Accepted Answer

Confidence intervals for model coefficients

Answer

confint() computes confidence intervals for the parameters of a fitted model, defaulting to 95% intervals.

Question 3

Which R function tests whether a numeric vector follows a normal distribution using the Shapiro-Wilk test?

Accepted Answer

shapiro.test()

Answer

shapiro.test() performs the Shapiro-Wilk normality test and returns a W statistic and p-value.

Question 4

What is the purpose of the predict() function in R?

Accepted Answer

Generate predicted values from a fitted model for new data

Answer

predict() uses a fitted model object to generate predictions for either the training data or new observations supplied via newdata=.

Question 5

Which R package provides tools for cross-validation and training machine learning models with a unified interface?

Accepted Answer

caret

Answer

caret (Classification And REgression Training) provides a unified interface for training, tuning, and evaluating hundreds of ML models.

R Programming Language Certification Practice Test