STT 231 Exam 3: Advanced Inference
(Newest 2026/2027 Update) Questions
and Verified Answers | 100% Correct
Grad A
STT 231 Exam 3 covers advanced inference, focusing on two-sample
procedures, chi-square tests, and regression analysis. It consists of 41
short-answer questions, and covers topics such as ANOVA, inference for
proportions/means, and interpreting computer output (RStudio).
Key Topics Covered (Exam 3):
Two-Sample Inference: Confidence intervals and hypothesis tests for
two independent means or proportions.
Chi-Square Tests: Goodness-of-Fit and tests of
independence/homogeneity.
Regression Analysis: Simple linear regression, correlation coefficient
of determination and introduction to multiple regression.
ANOVA (Analysis of Variance): Testing equality of multiple means
and applying Tukey’s HSD.
Study Design/Concepts: Pseudo replication, blocking, and
randomization.
Exam Structure and Tips:
Format: Short answer and conceptual questions, similar to Course
Hero examples.
Tools: Ability to interpret RStudio output is frequently required.
Preparation: Review past Grade scope and peer writing assignments.
1
, Materials: Typically, one sheet of paper (one-sided) allowed for notes
Quiz_________________?
A study was conducted to identify the factors affecting quality of sleep for
university students. A survey of 290 students of different majors aged 17-29 years
old revealed that 67.2% of these students suffered from poor sleep.Further
analyses were conducted based off the original study of 290 university students in
the question above. A second study assessed if the distribution of sleep quality
was the same for the various age groups of Young (19 years old or younger),
Middle (over19 but less than 24 years old), and Old (24 years and older)
university students. The following data shows the sleep quality results for each
group.a. Select the name of the test that should be used to assess if the
distribution of the responses is the same for the three age-group populations
𝜒 ^2 test of independence or 𝜒^2 goodness of fit test -
Answer
𝜒^2 test of independence
Quiz_________________?
chi squared test of independence -
Answer
A statistical test in which both variables are categorical. This test generally tells us
if the distribution of participants across categories is different from what would
happen if there were no difference between the groups
Quiz_________________?
Squared test statistic has two consequences -
2
, Answer
1. all x^2 statistics are positive
2. cells that are already unusual are further emphasized (side effect)
Quiz_________________?
Chi-square distributions are skewed to the ______ and take on only _______
values. -
Answer
Right, positive
Quiz_________________?
What is standard deviation in chi-squared? -
Answer
sqrt(2df)
Quiz_________________?
chi squared goodness of fit -
Answer
A hypothesis test that assesses whether the distribution of a single categorical
variable follows a proposed distribution.
3
(Newest 2026/2027 Update) Questions
and Verified Answers | 100% Correct
Grad A
STT 231 Exam 3 covers advanced inference, focusing on two-sample
procedures, chi-square tests, and regression analysis. It consists of 41
short-answer questions, and covers topics such as ANOVA, inference for
proportions/means, and interpreting computer output (RStudio).
Key Topics Covered (Exam 3):
Two-Sample Inference: Confidence intervals and hypothesis tests for
two independent means or proportions.
Chi-Square Tests: Goodness-of-Fit and tests of
independence/homogeneity.
Regression Analysis: Simple linear regression, correlation coefficient
of determination and introduction to multiple regression.
ANOVA (Analysis of Variance): Testing equality of multiple means
and applying Tukey’s HSD.
Study Design/Concepts: Pseudo replication, blocking, and
randomization.
Exam Structure and Tips:
Format: Short answer and conceptual questions, similar to Course
Hero examples.
Tools: Ability to interpret RStudio output is frequently required.
Preparation: Review past Grade scope and peer writing assignments.
1
, Materials: Typically, one sheet of paper (one-sided) allowed for notes
Quiz_________________?
A study was conducted to identify the factors affecting quality of sleep for
university students. A survey of 290 students of different majors aged 17-29 years
old revealed that 67.2% of these students suffered from poor sleep.Further
analyses were conducted based off the original study of 290 university students in
the question above. A second study assessed if the distribution of sleep quality
was the same for the various age groups of Young (19 years old or younger),
Middle (over19 but less than 24 years old), and Old (24 years and older)
university students. The following data shows the sleep quality results for each
group.a. Select the name of the test that should be used to assess if the
distribution of the responses is the same for the three age-group populations
𝜒 ^2 test of independence or 𝜒^2 goodness of fit test -
Answer
𝜒^2 test of independence
Quiz_________________?
chi squared test of independence -
Answer
A statistical test in which both variables are categorical. This test generally tells us
if the distribution of participants across categories is different from what would
happen if there were no difference between the groups
Quiz_________________?
Squared test statistic has two consequences -
2
, Answer
1. all x^2 statistics are positive
2. cells that are already unusual are further emphasized (side effect)
Quiz_________________?
Chi-square distributions are skewed to the ______ and take on only _______
values. -
Answer
Right, positive
Quiz_________________?
What is standard deviation in chi-squared? -
Answer
sqrt(2df)
Quiz_________________?
chi squared goodness of fit -
Answer
A hypothesis test that assesses whether the distribution of a single categorical
variable follows a proposed distribution.
3
