STAT 1000 EXAM 2 QUESTIONS AND 100%
CORRECT ANSWERS!!
two variables are associated if
values from one variable tend to be related to the values of the other variables
a graphical display of the relationship between two quantitative variables
scatterplot
in a scatterplot, what does the x axis usually represent and what does the vertical axis
usually represent
x axis = explanatory variable
y axis = response variable
what does each point on a scatterplot represent
it is an ordered pair, which includes the explanatory and response variable
what 3 things do we use to describe a scatter plot
direction, form, and strength
what direction can a scatter plot be in
positive, neither, or negative
what form can a scatterplot be in
linear, curved, or no pattern
what strength can scatterplots have (how tightly clustered together are the points)
weak, moderate, strong
how can we describe the strength of a scatterplot numerically
correlation coefficient
, a numerical measure of the direction and strength of a linear association between two
quantitative variables
correlation coefficient
what range can a correlation coefficient be
-1 and 1
the sign of the correlation coefficient describes the ? of the linear relationship
direction
the actual number between -1 and 1 for a correlation coefficient describes the ? of the
linear relationship
strength
parameter notation for correlation coefficient
p
statistic notation for correlation coefficient
r
*look at page 6 of notes for how to calculate correlation coeficient
a measure of the joint variability between two quantitative variables
covariance
the variance is never negative, why?
because it is a squared term
can the covariance be negative
yes
what does a positive covariance mean
there is a positive relationship, if one variable increases, so does the other one
CORRECT ANSWERS!!
two variables are associated if
values from one variable tend to be related to the values of the other variables
a graphical display of the relationship between two quantitative variables
scatterplot
in a scatterplot, what does the x axis usually represent and what does the vertical axis
usually represent
x axis = explanatory variable
y axis = response variable
what does each point on a scatterplot represent
it is an ordered pair, which includes the explanatory and response variable
what 3 things do we use to describe a scatter plot
direction, form, and strength
what direction can a scatter plot be in
positive, neither, or negative
what form can a scatterplot be in
linear, curved, or no pattern
what strength can scatterplots have (how tightly clustered together are the points)
weak, moderate, strong
how can we describe the strength of a scatterplot numerically
correlation coefficient
, a numerical measure of the direction and strength of a linear association between two
quantitative variables
correlation coefficient
what range can a correlation coefficient be
-1 and 1
the sign of the correlation coefficient describes the ? of the linear relationship
direction
the actual number between -1 and 1 for a correlation coefficient describes the ? of the
linear relationship
strength
parameter notation for correlation coefficient
p
statistic notation for correlation coefficient
r
*look at page 6 of notes for how to calculate correlation coeficient
a measure of the joint variability between two quantitative variables
covariance
the variance is never negative, why?
because it is a squared term
can the covariance be negative
yes
what does a positive covariance mean
there is a positive relationship, if one variable increases, so does the other one
