MATH 225N STATISTICS EXAM SCRIPT
COMPREHENSIVE STUDY GUIDE
●● Bivariate data
Answer: data that consists of ordered pairs
●● Scatterplot
Answer: used to study bivariate data
●● Positive association
Answer: two variables, large values of one associated with large values
of the other
●● Least-squares regression line
Answer: Line that fits best is the line for which this sum of squared
distances is as small as possible (p 493)
●● Negative association
Answer: large values of one associated with small values of the other
●● Linear relationship
,Answer: data tends to cluster around a straight line when plotted on a
scatterplot
●● Correlation coefficient
Answer: Summary statistic most often used to measure the closeness of
the relationship between two variables
~*sensitive to outliers*
●● r is positive
Answer: two variables have a positive linear association
●● r is negative
Answer: two variables have a negative linear association
●● r is close to 0
Answer: linear association is weak
●● r is closer to 1
Answer: more strongly positive linear assoc.
●● r is closer to -1
Answer: more strongly negative linear assoc.
, ●● r=1
Answer: points lie exactly on a straight line with positive slope
●● r=-1
Answer: points lie exactly on a straight line with negative slope
●● Can use least-squares regression line to predict value of outcome
variable (y hat), given ______________
Answer: explanatory variable
●● Point of averages
Answer: Least-squares regression line goes through point of averages
●● Residual
Answer: difference between observed value and predicted value
Residual = y - y (hat)
●● Arithmetic mean (mean)
Answer: Add the values and divide by the number of values in the set.
●● Which is influenced by extreme values more? (Mean or median?)
Answer: Mean!
COMPREHENSIVE STUDY GUIDE
●● Bivariate data
Answer: data that consists of ordered pairs
●● Scatterplot
Answer: used to study bivariate data
●● Positive association
Answer: two variables, large values of one associated with large values
of the other
●● Least-squares regression line
Answer: Line that fits best is the line for which this sum of squared
distances is as small as possible (p 493)
●● Negative association
Answer: large values of one associated with small values of the other
●● Linear relationship
,Answer: data tends to cluster around a straight line when plotted on a
scatterplot
●● Correlation coefficient
Answer: Summary statistic most often used to measure the closeness of
the relationship between two variables
~*sensitive to outliers*
●● r is positive
Answer: two variables have a positive linear association
●● r is negative
Answer: two variables have a negative linear association
●● r is close to 0
Answer: linear association is weak
●● r is closer to 1
Answer: more strongly positive linear assoc.
●● r is closer to -1
Answer: more strongly negative linear assoc.
, ●● r=1
Answer: points lie exactly on a straight line with positive slope
●● r=-1
Answer: points lie exactly on a straight line with negative slope
●● Can use least-squares regression line to predict value of outcome
variable (y hat), given ______________
Answer: explanatory variable
●● Point of averages
Answer: Least-squares regression line goes through point of averages
●● Residual
Answer: difference between observed value and predicted value
Residual = y - y (hat)
●● Arithmetic mean (mean)
Answer: Add the values and divide by the number of values in the set.
●● Which is influenced by extreme values more? (Mean or median?)
Answer: Mean!
