PSTAT 5LS - Exam 1 UPDATED ACTUAL
Exam Questions and CORRECT Answers
quantitative variable (or numerical/measurement variable) - CORRECT ANSWER -
measures or counts sm and are expressed as numbers Iie height or weight)
categorical variable (or qualitative variable) - CORRECT ANSWER - places an indv /
item into one of several groups or categories called levels (ie gender or major)
dot plot - CORRECT ANSWER - ideal for small data sets, but not become clustered w too
many values (extreme values)
histograms - CORRECT ANSWER - ideal for larger data sets w many unique values
SOCS - CORRECT ANSWER - shape (mode/symmetry), outlier, center (identify center,
using mean or median), spread (measure variability using SD or IQR)
modes - CORRECT ANSWER - the number of peaks/humps in distribution (ie unimodal,
bimodal, multimodal)
symmetry - CORRECT ANSWER - mirrored at its midpoint; lack of symmetry is skewed
left or skewed right
outliers - CORRECT ANSWER - observations that fall outside the overall pattern of the
distribution
population - CORRECT ANSWER - the entire group we want to learn about
sample - CORRECT ANSWER - a subset of indvs from the population
, parameter - CORRECT ANSWER - a numerical summary of the population (ie the
average age of ALL UCSB students) - rarely known
statistic - CORRECT ANSWER - a numerical summary of the sample (ie the average age
of 500 SAMPLED UCSB students)
measures of center - CORRECT ANSWER - provides overall summary of where most
data points are located; mean and median
sample mean - CORRECT ANSWER - average of all observations (sum of all
observations / sample size)
sample median - CORRECT ANSWER - middle value when data is ordered (if there is an
even number, take the average of 2 middle values)
how do extreme observations impact the mean and median? - CORRECT ANSWER - the
mean is sensitive to extreme observations (shifts significantly), the median is resistant
what does symmetry and skew tell us about the mean and median? - CORRECT
ANSWER - symmetric: mean and median are close together
skewed to the right: mean > median
skewed to the left: mean < median
measures of variability - CORRECT ANSWER - essential for describing how
tightly/loosely the observations in the data are clustered around the center
range - CORRECT ANSWER - a way to describe variability, but sometimes unreliable
when dealing w extreme values (highly sensitive)
Exam Questions and CORRECT Answers
quantitative variable (or numerical/measurement variable) - CORRECT ANSWER -
measures or counts sm and are expressed as numbers Iie height or weight)
categorical variable (or qualitative variable) - CORRECT ANSWER - places an indv /
item into one of several groups or categories called levels (ie gender or major)
dot plot - CORRECT ANSWER - ideal for small data sets, but not become clustered w too
many values (extreme values)
histograms - CORRECT ANSWER - ideal for larger data sets w many unique values
SOCS - CORRECT ANSWER - shape (mode/symmetry), outlier, center (identify center,
using mean or median), spread (measure variability using SD or IQR)
modes - CORRECT ANSWER - the number of peaks/humps in distribution (ie unimodal,
bimodal, multimodal)
symmetry - CORRECT ANSWER - mirrored at its midpoint; lack of symmetry is skewed
left or skewed right
outliers - CORRECT ANSWER - observations that fall outside the overall pattern of the
distribution
population - CORRECT ANSWER - the entire group we want to learn about
sample - CORRECT ANSWER - a subset of indvs from the population
, parameter - CORRECT ANSWER - a numerical summary of the population (ie the
average age of ALL UCSB students) - rarely known
statistic - CORRECT ANSWER - a numerical summary of the sample (ie the average age
of 500 SAMPLED UCSB students)
measures of center - CORRECT ANSWER - provides overall summary of where most
data points are located; mean and median
sample mean - CORRECT ANSWER - average of all observations (sum of all
observations / sample size)
sample median - CORRECT ANSWER - middle value when data is ordered (if there is an
even number, take the average of 2 middle values)
how do extreme observations impact the mean and median? - CORRECT ANSWER - the
mean is sensitive to extreme observations (shifts significantly), the median is resistant
what does symmetry and skew tell us about the mean and median? - CORRECT
ANSWER - symmetric: mean and median are close together
skewed to the right: mean > median
skewed to the left: mean < median
measures of variability - CORRECT ANSWER - essential for describing how
tightly/loosely the observations in the data are clustered around the center
range - CORRECT ANSWER - a way to describe variability, but sometimes unreliable
when dealing w extreme values (highly sensitive)
