STT 231 Exam 1

Terms and Definitions

Why is this statement not a variable?
"Average amount of sleep in the past 24 hours among students in our class."

A variable represents something measured for each case. The italicized quantity summarizes ALL cases simultaneously.

For a right-skewed test, is the mean or median greater

The mean is greater

For a left-skewed test, is the mean or median greater

The median is greater

what kind of distribution is this

Right Skewed

What kind of distribution is this

Left Skewed

What symbol represents the proportion measured for a sample?

pi hat

What symbol represents the proportion measured for a population?

pi

What symbol represents the mean measured for a sample?

X bar

What symbol represents the mean measured for a population?

Mu

What symbol represents the median measured for a sample?

X\~

What symbol represents the median measured for a population?

Mu bar

What symbol represents the standard deviation measured for a sample?

S

What symbol represents the standard deviation measured for a population?

lowercase sigma

Can the standard deviation ever be negative?

Never

Can the Z-Score be negative?

Sometimes

Can the IQR be negative?

Never

Can the P-Value be negative?

Never

Can the correlation coefficient be negative?

Sometimes

What is a nominal variable

A nominal variable is a type of categorical variable that consists of values that have no inherent order or numerical significance. Nominal variables are typically used to classify data into distinct groups or categories based on some characteristic or attribute.

Example of nominal variables:

* Gender: Male, Female, Non-binary

What is a discrete variable

A discrete variable is a type of quantitative variable that can only take on a finite or countable set of values. Discrete variables can only assume certain numerical values, and the values cannot be subdivided into smaller units or intervals.

Examples of discrete variables include:

* Number of children in a family (can only be a whole number)
* How many problems did you get right on an exam (can only be a certain number, up to the number of questions on the exam)

What is a continuous variable

A continuous variable is a type of quantitative variable that can take on any value within a certain range. Unlike discrete variables, continuous variables can be subdivided into smaller and smaller units or intervals, and can assume an infinite number of possible values.

Example of continuous variables:

* Height of individuals (can be measured to any degree of accuracy)

What is an ordinal variable

An ordinal variable is a type of categorical variable that consists of values that can be ordered or ranked based on some inherent property or characteristic. Unlike nominal variables, ordinal variables have a meaningful order or sequence between categories, but the differences between categories are not necessarily equal.

Example of ordinal variables:

* Educational level: High school, Associate’s Degree, Bachelor's degree, Master's degree, PhD

What symbol represents the number of members measured for a sample?

n

What symbol represents the number of members measured for a population?

N