R Programming Language Certification Statistical Analysis & Modeling

Question 1

Which function in R fits a linear regression model?

Accepted Answer

lm()

Answer

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

Question 2

What does the p-value in a t-test represent?

Accepted Answer

The probability of observing results as extreme as observed, assuming H0 is true

Answer

The p-value is the probability of obtaining a test statistic as extreme as or more extreme than the observed value, assuming the null hypothesis is true.

Question 3

Which function performs a Shapiro-Wilk test for normality in R?

Accepted Answer

shapiro.test()

Answer

shapiro.test() performs the Shapiro-Wilk test, which evaluates whether a sample comes from a normally distributed population.

Question 4

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

Accepted Answer

Computes correlation coefficients between variables

Answer

cor() computes pairwise correlation coefficients (Pearson by default) measuring linear association between numeric variables.

Question 5

Which function performs a one-way ANOVA in R?

Accepted Answer

aov()

Answer

aov() fits an analysis of variance model and can be followed by summary() to display the ANOVA table with F-statistics and p-values.

R Programming Language Certification Practice Test

R Programming Language Certification Practice Test

R Programming Language Certification Statistical Analysis & Modeling