STAT 201 EXAM 2 VERIFIED ACCURATE STUDY
GUIDE
subject - Answers - person, animal, object of interest
variable - Answers - characteristics that we measure on the subject
population - Answers - all subjects of interest
sample - Answers - subset of our population
statistic - Answers - numerical summary of the sample
parameter - Answers - numerical summary of the population
categorical variable - Answers - qualitiative, no numerical meaning
quantitative variable - Answers - take on values
discrete - Answers - finite value
continuous - Answers - any value (within a range)
descriptive - Answers - methods, averages, and percentages, only report of data
inferential - Answers - data used to make predictions
mean - Answers - sigma xi/n, always unique sensitive to outliers
median - Answers - midpoint of data n+1/2, robust to outliers
mode - Answers - number that occurs most often (quantitative description), unique, can
be used for categorical data
dispersion - Answers - spread or variability
range - Answers - lowest and highest value, bc it looks at the extremes max-min
standard deviation - Answers - s (sample standard) measures variation by summarizing
the deviations of each observation from the mean and then calculates the average
NEVER NEGATIVE s=square root[(xi-x)^2/n-1]
the larger it is the more spread out the data, affected by outliers
, variance - Answers - s^2 (sample variance) (xi-x)^2/n-1
Q1 - Answers - .25(n+1)
Q2 - Answers - .5(n+1)
Q3 - Answers - .75(n+1)
low outlier formula - Answers - Q1-1.5 x IQR
high outlier formula - Answers - Q3 + 1.5 X IQR
five number summary - Answers - min
Q1
Q2
Q3
max
no mode - Answers - 3+ the same
explanatory variable - Answers - independent variable, defines group to compare
response variable - Answers - dependent variable, outcome variable on which
comparisons are made
contingency table - Answers - both variables categorical, display frequencies on the
table
form - Answers - also known as shape: linear, curved, quadratic, random, used on
scatter plots
direction - Answers - increasing (positive) decreasing (negative), used on scatter plots
strength - Answers - strong, moderate, weak, used on scatter plots
correlation coefficient - Answers - summarizes the direction and strength of a linear
relationship
sample correlation - Answers - r=1/(n-1) sigma [(xi-x)/sx] x [(xi-x)/sy]
affected y outliers
negative r - Answers - data is decreasing
positive r - Answers - data is increasing
r range - Answers - -1 - 1
GUIDE
subject - Answers - person, animal, object of interest
variable - Answers - characteristics that we measure on the subject
population - Answers - all subjects of interest
sample - Answers - subset of our population
statistic - Answers - numerical summary of the sample
parameter - Answers - numerical summary of the population
categorical variable - Answers - qualitiative, no numerical meaning
quantitative variable - Answers - take on values
discrete - Answers - finite value
continuous - Answers - any value (within a range)
descriptive - Answers - methods, averages, and percentages, only report of data
inferential - Answers - data used to make predictions
mean - Answers - sigma xi/n, always unique sensitive to outliers
median - Answers - midpoint of data n+1/2, robust to outliers
mode - Answers - number that occurs most often (quantitative description), unique, can
be used for categorical data
dispersion - Answers - spread or variability
range - Answers - lowest and highest value, bc it looks at the extremes max-min
standard deviation - Answers - s (sample standard) measures variation by summarizing
the deviations of each observation from the mean and then calculates the average
NEVER NEGATIVE s=square root[(xi-x)^2/n-1]
the larger it is the more spread out the data, affected by outliers
, variance - Answers - s^2 (sample variance) (xi-x)^2/n-1
Q1 - Answers - .25(n+1)
Q2 - Answers - .5(n+1)
Q3 - Answers - .75(n+1)
low outlier formula - Answers - Q1-1.5 x IQR
high outlier formula - Answers - Q3 + 1.5 X IQR
five number summary - Answers - min
Q1
Q2
Q3
max
no mode - Answers - 3+ the same
explanatory variable - Answers - independent variable, defines group to compare
response variable - Answers - dependent variable, outcome variable on which
comparisons are made
contingency table - Answers - both variables categorical, display frequencies on the
table
form - Answers - also known as shape: linear, curved, quadratic, random, used on
scatter plots
direction - Answers - increasing (positive) decreasing (negative), used on scatter plots
strength - Answers - strong, moderate, weak, used on scatter plots
correlation coefficient - Answers - summarizes the direction and strength of a linear
relationship
sample correlation - Answers - r=1/(n-1) sigma [(xi-x)/sx] x [(xi-x)/sy]
affected y outliers
negative r - Answers - data is decreasing
positive r - Answers - data is increasing
r range - Answers - -1 - 1
