Intro to Stats Exam 1 SLCC UPDATED
ACTUAL Questions and CORRECT
Answers
Coefficent of Variation (CV) - CORRECT ANSWER - Ratio of the standard deviation to
the mean of data set
Std. dev / mean
Higher CV = more spread
When converting units of measure, the CV is unchanged
Statcrunch = coef of var (displayed as percentage, don't forget to divide by 100)
Empirical Rule - CORRECT ANSWER - For bell-curve data
68% of data within 1 std dev
95% within 2 std dev
99.7% within 3 std dev
sample standard deviation - CORRECT ANSWER -s
Statcrunch = std dev
population standard deviation - CORRECT ANSWER - σ (sigma)
Statcrunch = unadj. std. dev
Random sampling - CORRECT ANSWER - a sample that fairly represents a population
because each member has an equal chance of inclusion
, ex: pull #'s out of hat
Systematic sampling - CORRECT ANSWER - randomly select some starting point and
then select every kth element in the population
ex: 5th customer to come out of store and then every 7th after that.
stratified sampling - CORRECT ANSWER - A type of probability sampling in which the
population is divided into groups with a common attribute and a random sample is chosen within
each group
homogeneous, non-overlapping strata
Ex: freshmen, soph, juniors and seniors could be strata
Cluster sampling - CORRECT ANSWER - A probability sampling technique in which
clusters of participants within the population of interest are selected at random, followed by data
collection from all individuals in each cluster.
Ex: randomly select cluster, like all 8 am classes, then sample every student in 4 of those courses
Determine value of k when N is known - CORRECT ANSWER - Ex: N=20,325 and you
want sample n=100
N/n = 20,325/100 = 203.5
Always round down to nearest integer so k=203
To calculate last person surveyed, take [(n-1) x k] + starting point. So if starting point is 90th
person, it goes 90, 293, 496 ....... -> (99x203) + 90 = 20,187
ACTUAL Questions and CORRECT
Answers
Coefficent of Variation (CV) - CORRECT ANSWER - Ratio of the standard deviation to
the mean of data set
Std. dev / mean
Higher CV = more spread
When converting units of measure, the CV is unchanged
Statcrunch = coef of var (displayed as percentage, don't forget to divide by 100)
Empirical Rule - CORRECT ANSWER - For bell-curve data
68% of data within 1 std dev
95% within 2 std dev
99.7% within 3 std dev
sample standard deviation - CORRECT ANSWER -s
Statcrunch = std dev
population standard deviation - CORRECT ANSWER - σ (sigma)
Statcrunch = unadj. std. dev
Random sampling - CORRECT ANSWER - a sample that fairly represents a population
because each member has an equal chance of inclusion
, ex: pull #'s out of hat
Systematic sampling - CORRECT ANSWER - randomly select some starting point and
then select every kth element in the population
ex: 5th customer to come out of store and then every 7th after that.
stratified sampling - CORRECT ANSWER - A type of probability sampling in which the
population is divided into groups with a common attribute and a random sample is chosen within
each group
homogeneous, non-overlapping strata
Ex: freshmen, soph, juniors and seniors could be strata
Cluster sampling - CORRECT ANSWER - A probability sampling technique in which
clusters of participants within the population of interest are selected at random, followed by data
collection from all individuals in each cluster.
Ex: randomly select cluster, like all 8 am classes, then sample every student in 4 of those courses
Determine value of k when N is known - CORRECT ANSWER - Ex: N=20,325 and you
want sample n=100
N/n = 20,325/100 = 203.5
Always round down to nearest integer so k=203
To calculate last person surveyed, take [(n-1) x k] + starting point. So if starting point is 90th
person, it goes 90, 293, 496 ....... -> (99x203) + 90 = 20,187
