STAT 325 Fall 2023 Practice Exam 1

Researchers want to estimate the average student loan debt of bachelor’s degree graduates in 2021. They obtained a group of 250 such graduates from public universities in 2021.

Identify the population the researchers are interested in studying.

• All graduates with a bachelor's degree in 2021

• The 250 graduates with a bachelor's degree in 2021

• All college graduates in 2021

Answer explanation

The population is ALL the observations in the group the researchers are interested in (so ALL the graduates in 2021 with a Bachelor's degree)

Researchers want to estimate the average student loan debt of bachelor’s degree graduates in 2021. They obtained a group of 250 such graduates from public universities in 2021.

Identify the sample in the situation above.

• All of the graduates with bachelor's degrees in 2021

• The group of 250 master's degree graduates from public universities in 2021.

• The group of 250 bachelor's degree graduates from public universities in 2021

Answer explanation

The 250 students is not all the graduates, it is just a sample the researchers selected.

The sample of 250 students had an average student loan debt of $32,800. A census in 2021 determined that the average amount of student loans that are owed by students who graduated from public universities in the United States with a bachelor’s degree in 2021 was $38,792.

Is the number $32,800 a parameter or a statistic?

• Parameter

• Statistic

• Neither

Answer explanation

Statistic because it directly relates to the sample (to the 250 graduates)

The sample of 250 students had an average student loan debt of $32,800. A census in 2021 determined that the average amount of student loans that are owed by students who graduated from public universities in the United States with a bachelor’s degree in 2021 was $38,792.

Is the number $38,792 a parameter or a statistic?

• Parameter

• Statistic

• Neither

Answer explanation

Parameter because it relates to the overall population (the census collects data on an entire population)

Classify the following measurement observed in a study as nominal, ordinal, interval, or ratio:

Calcium level in blood (in micrograms per milliliter)

• nominal
• ordinal
• interval
• ratio

Answer explanation

Ratio because the calcium level in blood has a "true 0" (e.g. there is a 0 value that would mean there is no calcium in the blood)

Classify the following measurement observed in a study as nominal, ordinal, interval, or ratio:

Has breathing difficulties (always, sometimes, rarely, never)

• nominal
• ordinal
• interval
• ratio

Answer explanation

Ordinal because breathing level is qualitative (categorical) and has a meaningful order to the categories

Classify the following measurement observed in a study as nominal, ordinal, interval, or ratio:

Primary type of exercise (jogging, walking, swimming, other, or none)

• nominal
• ordinal
• interval
• ratio

Answer explanation

Nominal because type of exercise is qualitative (categorical) but the order of the categories is not meaningful

Classify the following measurement observed in a study as nominal, ordinal, interval, or ratio:

Resting heart rate (number of beats per minute)

• nominal
• ordinal
• interval
• ratio

Answer explanation

Ratio because resting heart rate has a "true 0" (e.g. there is a 0 value that would mean you don't have a heart rate)

Classify the following measurement observed in a study as nominal, ordinal, interval, or ratio:

Minimum body temperature while asleep at night (degrees Fahrenheit)

• nominal
• ordinal
• interval
• ratio

Answer explanation

Interval because body temp in Fahrenheit is quantitative (numeric) but does not have a "true 0" (e.g. a temp of 0F does not mean there is "no temperature")

Classify the following measurement observed in a study as nominal, ordinal, interval, or ratio:

Takes medicine containing a calcium channel blocker (yes or no)

• nominal
• ordinal
• interval
• ratio

Answer explanation

Nominal because whether or not someone takes a medication is qualitative (categorical) but the order of the categories is not meaningful