R Programming Language Certification Statistical Analysis & Modeling in R

Question 1

Which R function fits a linear regression model?

Accepted Answer

lm()

Answer

lm() fits ordinary least squares linear models and returns an object with coefficients, residuals, and fit statistics.

Question 2

What does the summary() function return when applied to a linear model in R?

Accepted Answer

Coefficients, standard errors, t-values, p-values, and R-squared

Answer

summary(lm_object) displays the regression table with estimates, standard errors, t-statistics, p-values, and model fit statistics.

Question 3

Which function performs a two-sample t-test in R?

Accepted Answer

t.test()

Answer

t.test() performs one-sample, two-sample, or paired t-tests and returns the t-statistic, p-value, and confidence interval.

Question 4

What does cor() compute in R?

Accepted Answer

The correlation coefficient between two or more variables

Answer

cor() computes Pearson (default), Spearman, or Kendall correlation coefficients between numeric vectors or columns.

Question 5

Which R function performs a one-way ANOVA?

Accepted Answer

aov()

Answer

aov() fits an analysis of variance model; use summary(aov_object) to see the F-statistic and p-value.

R Programming Language Certification Practice Test