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STT 215 Exam 1 Questions and Answers (100%
Correct Answers) Already Graded A+
What is statistics? Ans: Collection or gathering of data
Displaying, analyzing, and summarizing data
Inferring information from data
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Cases Ans: The objects described by a set of data. May be customers,
companies, subjects in a study, or other subjects
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(observations/individuals).
Label Ans: A special variable used in some data sets to distinguish
different cases.
Example: Patient A, Patient B, Patient C, etc.
Variable Ans: 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
Distribution Ans: Tells us what values the variable takes and how often it
takes these values.
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Categorical variable Ans: 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 Ans: Something that can be counted
or measured for each individual and then added, subtracted,
averaged, etc. across individuals in the population.
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Example: height, age, blood cholesterol level
Quantitative data: discrete versus continous Ans: Discrete if the possible
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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 Ans: Frequency / Relative
Frequency distribution
Bar graph
Pie chart
Ways to represent numerical data Ans: Frequency distribution
Stemplot (stem-and-leaf plot)
Histogram
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Ways to represent bivariate numerical data Ans: Scatter plot
Bar graph Ans: Each category is represented by a bar. The bar's height
shows the count (or sometimes the percentage) for that particular
category.
Pie chart Ans: 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.
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Relative frequency Ans: (frequency) / (number of observations in the
data set)
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Stemplot Ans: (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.
Display the actual values of the observations.
How to make a stemplot Ans: Separate each observation into a stem
(consisting of all but the final (rightmost) digit), and a leaf (which is that
remaining final digit). Stems may have as many digits as needed, but
each leaf contains only a single digit.
Write the stems in a vertical column with the smallest value at the top,
and draw a vertical line at the right of this column.
Write each lead in the row of its stem, in increasing order out from the
stem.
1
STT 215 Exam 1 Questions and Answers (100%
Correct Answers) Already Graded A+
What is statistics? Ans: Collection or gathering of data
Displaying, analyzing, and summarizing data
Inferring information from data
© 2026 Assignment Expert
Cases Ans: The objects described by a set of data. May be customers,
companies, subjects in a study, or other subjects
Guru01 - Stuvia
(observations/individuals).
Label Ans: A special variable used in some data sets to distinguish
different cases.
Example: Patient A, Patient B, Patient C, etc.
Variable Ans: 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
Distribution Ans: Tells us what values the variable takes and how often it
takes these values.
,For Expert help and assignment handling,
2
Categorical variable Ans: 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 Ans: Something that can be counted
or measured for each individual and then added, subtracted,
averaged, etc. across individuals in the population.
© 2026 Assignment Expert
Example: height, age, blood cholesterol level
Quantitative data: discrete versus continous Ans: Discrete if the possible
Guru01 - Stuvia
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 Ans: Frequency / Relative
Frequency distribution
Bar graph
Pie chart
Ways to represent numerical data Ans: Frequency distribution
Stemplot (stem-and-leaf plot)
Histogram
, For Expert help and assignment handling,
3
Ways to represent bivariate numerical data Ans: Scatter plot
Bar graph Ans: Each category is represented by a bar. The bar's height
shows the count (or sometimes the percentage) for that particular
category.
Pie chart Ans: 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.
© 2026 Assignment Expert
Relative frequency Ans: (frequency) / (number of observations in the
data set)
Guru01 - Stuvia
Stemplot Ans: (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.
Display the actual values of the observations.
How to make a stemplot Ans: Separate each observation into a stem
(consisting of all but the final (rightmost) digit), and a leaf (which is that
remaining final digit). Stems may have as many digits as needed, but
each leaf contains only a single digit.
Write the stems in a vertical column with the smallest value at the top,
and draw a vertical line at the right of this column.
Write each lead in the row of its stem, in increasing order out from the
stem.
