2811 Midterm Question and answers
already passed 2025
Descriptive Statistics - correct answer Form of data analysis that produces
meaningful summaries of data patterns
Can see patterns, uncertainty, facts
Allow us to make estimates of population from a sample (needed to make
inferences)
Inferences Require - correct answer Good experimental Design
Representative sample
Accurate theories (close enough to truth or a reasonable description)
Start with facts obtained from data set (population, sampling methods,
randomization methods, relationships between variables, distribution of data,
central trends)
Graphs should - correct answer show:
distribution
patterns
quick understanding
be free of:
chart junk
lie factor
data:ink ratio (prop of graphics ink devoted to display of data)
,central tendency - correct answer mean, median, mode
histogram - correct answer - x-axis : individual value, y-axis: frequency
- estimate of how data would be distributed in the population
- quantitative
- first create a frequency table in which scores are grouped together as class
intervals with class frequencies
- can be used for whole of continuous numbers
- when using continuous variables whole numbers used as bounds
- can change to relative frequency by dividing each class frequency by total #
of observations then plotting quotients on y-axis
Box Plot - correct answer uses median not mean
IQR: Q3-Q1
lower fence: Q1-1.5x IQR
upper fence: Q3+ 1.5 x IQR
box plots preferred to stem lead display when
1) there is a large amount of data and
2) more than two groups are compared
- stem/leaf show individual values and skew well
Dispersion - correct answer how spread out data points are
range: max value - min value
IQR
, Variance: average squared deviation from mean
SD: average deviation from mean in units of original measurement
Variance - correct answer how close scores are to the middle of distribution
average squared differance from mean
mean deviation from mean = zero
Bessel's correction is used in sample SD/Variance as the formula for variance
in a population would underestimate in a sample
standard deviation - correct answer - useful measure of variability when
distribution is normal
- prop of distribution within a given number of SD can be calculated
POP variance formula - correct answer
SAMPLE variance formula - correct answer
Violin plot - correct answer box plot +"kernal density estimate" - more
informative
3 ways of thinking about center of distribution - correct answer Balance scale:
point to which the distribution is in balance
Smallest absolute deviation: # for which sum of absoulte deviations is the
smallest
already passed 2025
Descriptive Statistics - correct answer Form of data analysis that produces
meaningful summaries of data patterns
Can see patterns, uncertainty, facts
Allow us to make estimates of population from a sample (needed to make
inferences)
Inferences Require - correct answer Good experimental Design
Representative sample
Accurate theories (close enough to truth or a reasonable description)
Start with facts obtained from data set (population, sampling methods,
randomization methods, relationships between variables, distribution of data,
central trends)
Graphs should - correct answer show:
distribution
patterns
quick understanding
be free of:
chart junk
lie factor
data:ink ratio (prop of graphics ink devoted to display of data)
,central tendency - correct answer mean, median, mode
histogram - correct answer - x-axis : individual value, y-axis: frequency
- estimate of how data would be distributed in the population
- quantitative
- first create a frequency table in which scores are grouped together as class
intervals with class frequencies
- can be used for whole of continuous numbers
- when using continuous variables whole numbers used as bounds
- can change to relative frequency by dividing each class frequency by total #
of observations then plotting quotients on y-axis
Box Plot - correct answer uses median not mean
IQR: Q3-Q1
lower fence: Q1-1.5x IQR
upper fence: Q3+ 1.5 x IQR
box plots preferred to stem lead display when
1) there is a large amount of data and
2) more than two groups are compared
- stem/leaf show individual values and skew well
Dispersion - correct answer how spread out data points are
range: max value - min value
IQR
, Variance: average squared deviation from mean
SD: average deviation from mean in units of original measurement
Variance - correct answer how close scores are to the middle of distribution
average squared differance from mean
mean deviation from mean = zero
Bessel's correction is used in sample SD/Variance as the formula for variance
in a population would underestimate in a sample
standard deviation - correct answer - useful measure of variability when
distribution is normal
- prop of distribution within a given number of SD can be calculated
POP variance formula - correct answer
SAMPLE variance formula - correct answer
Violin plot - correct answer box plot +"kernal density estimate" - more
informative
3 ways of thinking about center of distribution - correct answer Balance scale:
point to which the distribution is in balance
Smallest absolute deviation: # for which sum of absoulte deviations is the
smallest
