Statistics Unit 2 Flashcards

Questions and Answers

Methods used that summarize or describe characteristics of data are called _______ statistics.

descriptive

A value at the center or middle of a data set is a(n) _______.

measure of center

Which of the following is NOT a measure of center?

Census (correct)

Mode

Mean

Median

The measure of center that is the value that occurs with the greatest frequency is the _______.

mode Signup and view all the answers

Which of the following is always true?

In a symmetric and bell-shaped distribution, the mean, median, and mode are the same Signup and view all the answers

If the standard deviation for a set of data is 0, which of the following must be true?

All of the data values are identical Signup and view all the answers

The Range Rule of Thumb roughly estimates the standard deviation of a data set as _______.

s = range/4 Signup and view all the answers

What is the role of the term average in statistics?

The term average is not used in statistics; the term mean should be used. Signup and view all the answers

The symbol for sample standard deviation is _______.

s Signup and view all the answers

The symbol for population standard deviation is _______.

σ Signup and view all the answers

The symbol for sample variance is _______.

s^2 Signup and view all the answers

The symbol for population variance is _______.

σ^2 Signup and view all the answers

If sample data consist of weights measured in grams, then the unit for sample standard deviation would be _______.

g Signup and view all the answers

The unit for population standard deviation would be _______.

g Signup and view all the answers

The unit for sample variance would be _______.

g^2 Signup and view all the answers

The unit for population variance would be _______.

g^2 Signup and view all the answers

For data sets having a distribution that is approximately bell-shaped, _______ states that about 68% of all data values fall within one standard deviation from the mean.

the Empirical Rule Signup and view all the answers

The square of the standard deviation is called the _______.

variance Signup and view all the answers

When a data value is converted to a standardized scale representing the number of standard deviations the data value lies from the mean, we call the new value a _______.

z-score Signup and view all the answers

Whenever a data value is less than the mean, _______.

the corresponding z-score is negative Signup and view all the answers

The 5-number summary includes _______.

min, Q1, median, Q3, max Signup and view all the answers

Which of the following is NOT a value in the 5-number summary?

Mean Signup and view all the answers

What do P(A) and P(Ā) represent when A denotes the event of selecting someone with blue eyes?

P(A) represents the probability of selecting an adult with blue eyes; P(Ā) represents the probability of selecting an adult who does not have blue eyes. Signup and view all the answers

When using the ______, always be careful to avoid double-counting outcomes.

addition rule Signup and view all the answers

Events that are _______ cannot occur at the same time.

disjoint Signup and view all the answers

What does P(B|A) represent?

The probability of event B occurring after it is assumed that event A has already occurred. Signup and view all the answers

Two events A and B are _______ if the occurrence of one does not affect the probability of the occurrence of the other.

independent Signup and view all the answers

'At least one' is equivalent to _______.

'one or more' Signup and view all the answers

A _______ probability of an event is a probability obtained with knowledge that some other event has already occurred.

conditional Signup and view all the answers

What is the probability of getting the correct Social Security number of the person who was given the receipt?

1/100,000 Signup and view all the answers

If radio station call letters must begin with either K or W and must include either two or three additional letters, how many different possibilities are there?

36504 Signup and view all the answers

Study Notes

Descriptive Statistics

Descriptive statistics summarize or describe characteristics of data without making conclusions beyond the data.
Measures of center include mean, median, and mode.

Measures of Center

The measure of center represents the middle value in a data set.
The mode is the most frequently occurring value, while the census is not a measure of center.
In a symmetric, bell-shaped distribution, the mean, median, and mode are equal.

Data Characteristics

A standard deviation of 0 indicates that all data values are identical.
The Range Rule of Thumb estimates standard deviation as ( s = \text{range}/4 ).

Terminology in Statistics

The term "average" is not used; "mean" refers to the sum of sample values divided by the total number of values.
Sample standard deviation is symbolized as ( s ), while population standard deviation is represented by ( \sigma ).

Variance

The sample variance is denoted by ( s^2 ) and population variance by ( \sigma^2 ).
Units for standard deviation in grams remain in grams (g), while variance is expressed in square grams (g²).

Empirical Rule

According to the Empirical Rule, approximately 68% of data values in a bell-shaped distribution fall within one standard deviation from the mean.

Standardized Scores

A z-score indicates how many standard deviations a data value is from the mean; scores below the mean yield negative z-scores.

Five-Number Summary

The five-number summary includes minimum, Q1, median, Q3, and maximum values, while the mean is not part of this summary.

Probability Concepts

The probability of event A (e.g., selecting someone with blue eyes) is denoted as ( P(A) ) and ( P(\bar{A}) ) represents the probability of the complementary event.
The addition rule requires careful application to avoid double-counting outcomes.

Event Relationships

Disjoint events cannot occur simultaneously, while independent events are unaffected by each other's occurrence.
Conditional probability ( P(B|A) ) describes the probability of event B occurring given that event A has occurred.

Probability of Events

"At least one" is synonymous with "one or more."
The probability of selecting the correct Social Security number after knowing partial digits is extremely low at ( \frac{1}{100,000} ).

Combinatorial Probability

For radio station call letters that start with K or W and have two or three additional letters, there are 36,504 unique combinations possible.

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Description

Test your knowledge of essential concepts in descriptive statistics with these flashcards. This quiz covers key definitions and measures of center, helping you to better understand how to summarize data. Great for students looking to reinforce their learning in statistics.