Sampling and Probability

Question 1

what is probability?

Answer 1

chance/likelihood of an event occurring

Question 2

what is the range of values in a probability statement?

Answer 2

between 0 and 1

Question 3

what is gambler’s fallacy?

Answer 3

belief that if you keep playing, you’ll win

Question 4

why is gambler’s fallacy false?

Answer 4

chances of winning are the same every time you play

Question 5

what is the law of large numbers?

Answer 5

if enough people play for a long amount of time, the house (casino) will always win

Question 6

in calculating birthdays and probability, why does the pairs concept apply?

Answer 6

there are more pairs of people than individuals

Question 7

what is a population?

Answer 7

entire set of units of analysis

Question 8

what is a sample?

Answer 8

a subset of the population

Question 9

what is a statistic?

Answer 9

characteristic of a sample

Question 10

what is a parameter?

Answer 10

characteristic of a population that always stays the same(realistically unknown)

Question 11

what should the statistic always mirror as close as possible?

Answer 11

the parameter

Question 12

what does difference between a statistic and the parameter mean?

Answer 12

error

Question 13

what are the 3 main challenges in sampling?

Answer 13

1. defining the population
2. selecting the sample design
3. deciding upon sample size

Question 14

what are the categories of sample design?

Answer 14

probability vs. non-probability

Question 15

what is probability theory?

Answer 15

everyone has an equal chance of selection for the sample

Question 16

what is poisson clumping?

Answer 16

certain events clutter together; randomness leads to clumping

Question 17

what is random selection?

Answer 17

each element has an equal chance of selection independent of any other events in the selection process

Question 18

what is representativeness?

Answer 18

having the same distribution of characteristics as the population

Question 19

what is bias?

Answer 19

systematic preference/predisposition to reach a particular conclusion

Question 20

what is non-probability sampling?

Answer 20

a sample selected in some fashion other than any suggested by probability theory

Question 21

what are the types of non-random sampling?

Answer 21

1. convenience - using only available subjects
2. purposive/judgemental - choosing ones you know you need
3. snowball - one person leads to another
4. quota - predetermined group selection
5. selecting informants - choosing person to inform you

Question 22

when can probability of selection not be determined?

Answer 22

when there’s no mention of sampling error in a study and/or if it can’t be generalized

Question 23

what is the relationship between sample size and sampling error?

Answer 23

the larger the sample size, the smaller the sampling error

Question 24

what is an inverse relationship?

Answer 24

a negative relationship, one decreases when one increases

Question 25

what are the 3 fallacies of sample size?

Answer 25

1. needs to be certain proportion of population
2. adequate sample size is about 2000
3. any increase in sample size increases precision of results

Question 26

what is sampling error?

Answer 26

difference between a population value and an estimate of that value derived from a sample

Question 27

what is a probability experiment?

Answer 27

a situation involving chance that leads to a measurable result

Question 28

what are the requirements of a probability experiment?

Answer 28

1. must have more than one possible outcome
2. each possible outcome can be specified in advance
3. outcome must be due to chance

Question 29

what is sampling distribution?

Answer 29

distribution of all possible outcomes for a statistic

Question 30

what is the central limit theorem?

Answer 30

the distribution of a sample’s mean will approach a normal curve as “n” and number of samples increase