STAT 2510 EXAM 1 HASKELL
QUESTIONS AND ANSWERS GRADED A+
2026
Why is obtaining a representative sample important? - ANS The sample must be
representative in order to use inferential statistics to draw conclusions about the entire
population
systematic sampling - ANS every nth member of the population is selected to be in the
sample; first person to start is chosen at random
what is a convenience sample? - ANS people who volunteer for the study; are easily
accessible, can be biased
- CANNOT BE GENERALIZED TO THE POPULATION
what is a simple random sample? - ANS Each member of the population has an equal chance
of being selected to be part of the sample, randomly selected
- CAN BE GENERALIZED TO THE POPULATION
- there is the possibility for a non-response bias: if so few people respond to the simple random
survey, the sample may no longer be representative of the population
convenience sample vs simple random sample - ANS convenience: possible bias, volunteers,
people who are easily accessible, cannot be generalized to the population
@COPYRIGHT 2026/2027 ALL RIGHTS RESERVED
1
, simple random: chosen randomly to participate, more representative; can be generalized to the
populationpra
stratified sampling - ANS the population is divided into a minimum of 2 groups called strata
(common characteristics), and then a random sample is taken from each group
cluster sampling - ANS Take an entire group of individuals but randomly select certain groups,
(ex study fresh soph and seniors but not juniors); and then study all the people in those groups
multistage sampling - ANS a probability sampling technique involving at least two stages: a
random sample of clusters followed by a random sample of people within the selected clusters
- you cluster the groups, and select only a few groups to sample, but only sample a few from
each group
what is the difference between an observational study and an experiment? -
ANS observational study: if its an observational study they all get the same treatment; shows
correlation
experiment: if its an experiment they all get a random treatment, an experiment is the only way
to show causation
observational study - ANS - they all get the same treatment
- SHOWS NO CAUSATION
- if its a random sample, its correlation statement can be generalized to the whole population
- if its a convenience sample, the correlation statement applies for the sample only. it is not
generalizable and is a bad observational study. SUCKS!
experiment - ANS - if an experiment is a convenience sample, it only shows causation to the
sample. (most experiments)
- Must be random sampling AND random assignment to be generalizable and show causation to
the entire population (ideal experiment)
@COPYRIGHT 2026/2027 ALL RIGHTS RESERVED
2
QUESTIONS AND ANSWERS GRADED A+
2026
Why is obtaining a representative sample important? - ANS The sample must be
representative in order to use inferential statistics to draw conclusions about the entire
population
systematic sampling - ANS every nth member of the population is selected to be in the
sample; first person to start is chosen at random
what is a convenience sample? - ANS people who volunteer for the study; are easily
accessible, can be biased
- CANNOT BE GENERALIZED TO THE POPULATION
what is a simple random sample? - ANS Each member of the population has an equal chance
of being selected to be part of the sample, randomly selected
- CAN BE GENERALIZED TO THE POPULATION
- there is the possibility for a non-response bias: if so few people respond to the simple random
survey, the sample may no longer be representative of the population
convenience sample vs simple random sample - ANS convenience: possible bias, volunteers,
people who are easily accessible, cannot be generalized to the population
@COPYRIGHT 2026/2027 ALL RIGHTS RESERVED
1
, simple random: chosen randomly to participate, more representative; can be generalized to the
populationpra
stratified sampling - ANS the population is divided into a minimum of 2 groups called strata
(common characteristics), and then a random sample is taken from each group
cluster sampling - ANS Take an entire group of individuals but randomly select certain groups,
(ex study fresh soph and seniors but not juniors); and then study all the people in those groups
multistage sampling - ANS a probability sampling technique involving at least two stages: a
random sample of clusters followed by a random sample of people within the selected clusters
- you cluster the groups, and select only a few groups to sample, but only sample a few from
each group
what is the difference between an observational study and an experiment? -
ANS observational study: if its an observational study they all get the same treatment; shows
correlation
experiment: if its an experiment they all get a random treatment, an experiment is the only way
to show causation
observational study - ANS - they all get the same treatment
- SHOWS NO CAUSATION
- if its a random sample, its correlation statement can be generalized to the whole population
- if its a convenience sample, the correlation statement applies for the sample only. it is not
generalizable and is a bad observational study. SUCKS!
experiment - ANS - if an experiment is a convenience sample, it only shows causation to the
sample. (most experiments)
- Must be random sampling AND random assignment to be generalizable and show causation to
the entire population (ideal experiment)
@COPYRIGHT 2026/2027 ALL RIGHTS RESERVED
2
