WGU Intro to Probability and Statistics
Questions & Answers 100% Correct
Population - ANSWER-The entire group that is the target of interest, not just people. Eg,
"the population of 1 bedroom apartments"
Sample - ANSWER-A subgroup of the population. Eg, "the 1 bedroom apartments with
dishwashers."
Steps in the statistics process - ANSWER-1. PRODUCE DATA (by studying a sample of
the population)
2. EXPLORATORY DATA ANALYSIS (Summarize data.)
3. PROBABILITY ANALYSIS (Determine how the sample may differ from the
population.)
4. INFERENCE (draw conclusions)
Data - ANSWER-pieces of info about individuals organized into variables
Individual - ANSWER-a particular person or object
Variable - ANSWER-a particular characteristic of the individual
Dataset - ANSWER-a set of data identified with particular circumstances. Typically
displayed in tables with rows as the individuals and columns as the variables
Quantitative vs Categorical/Qualitative variables - ANSWER-Quantitaive: Numerical
values. Represent a measurement.
Categorical: category or label values into which individuals are grouped.
Three steps in Exploratory Data Analysis - ANSWER-1. Organize and SUMMARIZE raw
data
2. DISCOVER important features and patterns and striking deviations.
3. INTERPRET findings in the context of the problem
Examining Distributions - ANSWER-exploring data obtained from one variable at a time
Examining Relationships - ANSWER-exploring data obtained from two variables at a
time
Distribution - ANSWER-what values the variable takes, how often
, Three types of graphical displays of categorical distributions - ANSWER-1. Pie Charts
2. Bar Charts
3. Pictogram
Bins - ANSWER-ranges of data to make charting easier, like a bar chart where each bar
shows a range like 70-80%
Numerical Summaries - ANSWER-category counts and percentages
Four types of Graphical displays of Quantitative Variables - ANSWER-1. Histogram
2. Stemplot
3. Dotplot
4. Boxplot
Histogram - ANSWER-like a bar chart but the x axis is numerical, in order. Eg: x axis is
years, y axis is Men's income and Women's income. Or, the x axis is number of hours
studied, and y axis is number of students falling into each number of hours studied
category.
4 ways to interpret a histogram - ANSWER-1. Shape - Symmetry/Skewness, Peakness
(Modality)
2. Center - midpoint
3. Spread - approx range covered by all the data
4. Outliers - observations that fall outside overall pattern
Symmetric distributions (on a histogram) - ANSWER-look symmetric. can be multi-
peaked, but symmetrical
Skewness (on a histogram) - ANSWER-data is skewed to the right or left because
outliers. (Careful because the histogram looks heavy to the opposite side than to that
which it is skewed. Think of the outliers as pulling a long tail out from the main data,
making it not symmetrical.)
Peakedness (on a histogram) (three types) - ANSWER-1. Unimodal (single peaked)
distribution
2. Bimodal (double peaked) distribution
3. Uniform distribution (Many peaks, all the same)
Stemplot (or stem and leaf plot) - ANSWER-1. Write all the "stems" down in a list, in
ascending numerical order. (The stems are all the numbers but the right most number.
Eg: dataset 34 35 36 347 367 the stems are 3, 3, 3, 34, 36, but you only use each
identical stem once, so it would be 3, 34, 36)
2. Draw a line to the right of the list
3. Write all the leaves next to the stem, and rearrange them in increasing order
Questions & Answers 100% Correct
Population - ANSWER-The entire group that is the target of interest, not just people. Eg,
"the population of 1 bedroom apartments"
Sample - ANSWER-A subgroup of the population. Eg, "the 1 bedroom apartments with
dishwashers."
Steps in the statistics process - ANSWER-1. PRODUCE DATA (by studying a sample of
the population)
2. EXPLORATORY DATA ANALYSIS (Summarize data.)
3. PROBABILITY ANALYSIS (Determine how the sample may differ from the
population.)
4. INFERENCE (draw conclusions)
Data - ANSWER-pieces of info about individuals organized into variables
Individual - ANSWER-a particular person or object
Variable - ANSWER-a particular characteristic of the individual
Dataset - ANSWER-a set of data identified with particular circumstances. Typically
displayed in tables with rows as the individuals and columns as the variables
Quantitative vs Categorical/Qualitative variables - ANSWER-Quantitaive: Numerical
values. Represent a measurement.
Categorical: category or label values into which individuals are grouped.
Three steps in Exploratory Data Analysis - ANSWER-1. Organize and SUMMARIZE raw
data
2. DISCOVER important features and patterns and striking deviations.
3. INTERPRET findings in the context of the problem
Examining Distributions - ANSWER-exploring data obtained from one variable at a time
Examining Relationships - ANSWER-exploring data obtained from two variables at a
time
Distribution - ANSWER-what values the variable takes, how often
, Three types of graphical displays of categorical distributions - ANSWER-1. Pie Charts
2. Bar Charts
3. Pictogram
Bins - ANSWER-ranges of data to make charting easier, like a bar chart where each bar
shows a range like 70-80%
Numerical Summaries - ANSWER-category counts and percentages
Four types of Graphical displays of Quantitative Variables - ANSWER-1. Histogram
2. Stemplot
3. Dotplot
4. Boxplot
Histogram - ANSWER-like a bar chart but the x axis is numerical, in order. Eg: x axis is
years, y axis is Men's income and Women's income. Or, the x axis is number of hours
studied, and y axis is number of students falling into each number of hours studied
category.
4 ways to interpret a histogram - ANSWER-1. Shape - Symmetry/Skewness, Peakness
(Modality)
2. Center - midpoint
3. Spread - approx range covered by all the data
4. Outliers - observations that fall outside overall pattern
Symmetric distributions (on a histogram) - ANSWER-look symmetric. can be multi-
peaked, but symmetrical
Skewness (on a histogram) - ANSWER-data is skewed to the right or left because
outliers. (Careful because the histogram looks heavy to the opposite side than to that
which it is skewed. Think of the outliers as pulling a long tail out from the main data,
making it not symmetrical.)
Peakedness (on a histogram) (three types) - ANSWER-1. Unimodal (single peaked)
distribution
2. Bimodal (double peaked) distribution
3. Uniform distribution (Many peaks, all the same)
Stemplot (or stem and leaf plot) - ANSWER-1. Write all the "stems" down in a list, in
ascending numerical order. (The stems are all the numbers but the right most number.
Eg: dataset 34 35 36 347 367 the stems are 3, 3, 3, 34, 36, but you only use each
identical stem once, so it would be 3, 34, 36)
2. Draw a line to the right of the list
3. Write all the leaves next to the stem, and rearrange them in increasing order
