STATISTICS PORTAGE CNSL 503 EXAM 3 ELITE
REVIEW WITH VERIFIED SOLVED QUESTIONS
AND ACCURATE ANSWERS
◍ Why is it important to have a representative sample? Answer: It is
important to have a representative sample, because we're trying to make
inferences about a certain population. In order to make correct
inferences about this population, the sample must reflect the population.
For instance, not having a representative sample is what called Literary
Digest to predict Alf Landon to win, when FDR actually won in a land
slide.
◍ Representative sample Answer: consists of members that possess the
same characteristics as those of the population
(e.g. age distribution)
◍ biased sample Answer: a sample that is not representative of the
population
◍ simple random sampling Answer: -every member of the population
has an equal chance of being selected for the sample
-the probability that each member is selected is independent of one
another
-computers are often used to generate random numbers
, -best for small sample sizes
◍ systematic sampling Answer: random sampling with a system in
which the starting point is random and each subsequent member selected
is based on a fixed interval (e.g. every 3rd person)
- the probability that each member is selected is not independent of one
another
-random samples can be achieved in a way that is more efficient than
simple random samlping
◍ stratified sampling Answer: is when you divide the population into
strata (typically based on age, gender, race, socioeconomic status) and
then you randomly select people to sample from each strata
(not everyone in a strata is studied)
-great for populations with subsections/ different characterstics
◍ cluster sampling Answer: is when you divide the population into
clusters such as the U.S. voters into voters by states, and then you
randomly select clusters (e.g. CA, NY, KY). From there, everyone in
that cluster is studied.
-great for very large populations
REVIEW WITH VERIFIED SOLVED QUESTIONS
AND ACCURATE ANSWERS
◍ Why is it important to have a representative sample? Answer: It is
important to have a representative sample, because we're trying to make
inferences about a certain population. In order to make correct
inferences about this population, the sample must reflect the population.
For instance, not having a representative sample is what called Literary
Digest to predict Alf Landon to win, when FDR actually won in a land
slide.
◍ Representative sample Answer: consists of members that possess the
same characteristics as those of the population
(e.g. age distribution)
◍ biased sample Answer: a sample that is not representative of the
population
◍ simple random sampling Answer: -every member of the population
has an equal chance of being selected for the sample
-the probability that each member is selected is independent of one
another
-computers are often used to generate random numbers
, -best for small sample sizes
◍ systematic sampling Answer: random sampling with a system in
which the starting point is random and each subsequent member selected
is based on a fixed interval (e.g. every 3rd person)
- the probability that each member is selected is not independent of one
another
-random samples can be achieved in a way that is more efficient than
simple random samlping
◍ stratified sampling Answer: is when you divide the population into
strata (typically based on age, gender, race, socioeconomic status) and
then you randomly select people to sample from each strata
(not everyone in a strata is studied)
-great for populations with subsections/ different characterstics
◍ cluster sampling Answer: is when you divide the population into
clusters such as the U.S. voters into voters by states, and then you
randomly select clusters (e.g. CA, NY, KY). From there, everyone in
that cluster is studied.
-great for very large populations
