1
STT 215 Exam 1 Questions with Answers (100% Correct
Answers)
What is statistics? Answer: Collection or gathering of data
Displaying, analyzing, and summarizing data
Inferring information from data
Cases Answer: The objects described by a set of data. May be
customers, companies, subjects in a study, or other subjects
(observations/individuals).
Label Answer: A special variable used in some data sets to distinguish
different cases.
Example: Patient A, Patient B, Patient C, etc.
Variable Answer: A characteristic that varies among individuals in a
population or in a sample (a subset of a population).
Example: age, height, blood pressure, ethnicity, leaf length, first
language
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Distribution Answer: Tells us what values the variable takes and how
often it takes these values.
Categorical variable Answer: Something that falls into one of several
categories. What can be counted is the count or proportion of
individuals in each category.
Example: blood type (A, B, AB, O), hair color, ethnicity
Quantitative (numerical) variable Answer: Something that can be
counted or measured for each individual and then added, subtracted,
averaged, etc. across individuals in the population.
Example: height, age, blood cholesterol level
Quantitative data: discrete versus continous Answer: Discrete if the
possible values are isolated points on the number line.
Continuous if the set of possible values forms an entire interval on the
number line.
Ways to represent categorical data Answer: Frequency / Relative
Frequency distribution
Bar graph
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Pie chart
Ways to represent numerical data Answer: Frequency distribution
Stemplot (stem-and-leaf plot)
Histogram
Ways to represent bivariate numerical data Answer: Scatter plot
Bar graph Answer: Each category is represented by a bar. The bar's
height shows the count (or sometimes the percentage) for that
particular category.
Pie chart Answer: Peculiarity: the slices mist represent the parts of one
whole (1 or 100%). The size of a slice depends on what percent of the
whole this category represents.
Relative frequency Answer: (frequency) / (number of observations in
the data set)
Stemplot Answer: (Also called a stem-and-leaf plot) Each observation
is represented by a stem, consisting of all digits except the final one,
which is the leaf.
Work best for small numbers of observations that are all greater than 0.
© 2025 All rights reserved
STT 215 Exam 1 Questions with Answers (100% Correct
Answers)
What is statistics? Answer: Collection or gathering of data
Displaying, analyzing, and summarizing data
Inferring information from data
Cases Answer: The objects described by a set of data. May be
customers, companies, subjects in a study, or other subjects
(observations/individuals).
Label Answer: A special variable used in some data sets to distinguish
different cases.
Example: Patient A, Patient B, Patient C, etc.
Variable Answer: A characteristic that varies among individuals in a
population or in a sample (a subset of a population).
Example: age, height, blood pressure, ethnicity, leaf length, first
language
© 2025 All rights reserved
,2
Distribution Answer: Tells us what values the variable takes and how
often it takes these values.
Categorical variable Answer: Something that falls into one of several
categories. What can be counted is the count or proportion of
individuals in each category.
Example: blood type (A, B, AB, O), hair color, ethnicity
Quantitative (numerical) variable Answer: Something that can be
counted or measured for each individual and then added, subtracted,
averaged, etc. across individuals in the population.
Example: height, age, blood cholesterol level
Quantitative data: discrete versus continous Answer: Discrete if the
possible values are isolated points on the number line.
Continuous if the set of possible values forms an entire interval on the
number line.
Ways to represent categorical data Answer: Frequency / Relative
Frequency distribution
Bar graph
© 2025 All rights reserved
, 3
Pie chart
Ways to represent numerical data Answer: Frequency distribution
Stemplot (stem-and-leaf plot)
Histogram
Ways to represent bivariate numerical data Answer: Scatter plot
Bar graph Answer: Each category is represented by a bar. The bar's
height shows the count (or sometimes the percentage) for that
particular category.
Pie chart Answer: Peculiarity: the slices mist represent the parts of one
whole (1 or 100%). The size of a slice depends on what percent of the
whole this category represents.
Relative frequency Answer: (frequency) / (number of observations in
the data set)
Stemplot Answer: (Also called a stem-and-leaf plot) Each observation
is represented by a stem, consisting of all digits except the final one,
which is the leaf.
Work best for small numbers of observations that are all greater than 0.
© 2025 All rights reserved
