1.1 sampling methods

Question 1

statistics

Answer 1

investigative process using 4 steps: 1. formulate questions 2. collect data needed to answer the questions 3. describe the data 4. draw conclusions using appropriate methods

Question 2

population

Answer 2

the collection of people about which the information is gathered from

Question 3

sample

Answer 3

a subset of a population, containing the people that are actually studied

Question 4

statistic

Answer 4

a number that describes a sample

Question 5

parameter

Answer 5

a number that describes a population

Question 6

simple random sampling

Answer 6

like a lottery, n is a sample chosen by a method, in which each collection of n population items is equally likely to make up the sample

Question 7

sample of convenience

Answer 7

a sample not drawn by a well-defined random method

Question 8

stratified

Answer 8

the population is divided into groups, aka strata, where the members of each stratum are similar in some way. then a simple random sample is drawn from each stratum. stratified sampling is useful when the strata differ from one another, but the individuals within a stratum tend to be alike.

Question 9

cluster

Answer 9

items are drawn from the population in groups, or clusters. Cluster sampling is useful when the population is too large and spread out for simple random sampling to be feasible. Cluster sampling is used extensively by U.s. government agencies in sampling the u.s. population to measure sociological factors such as income and unemployment.

Question 10

systematic

Answer 10

the population items are ordered like walking alongside a line of people and choosing every third one. It is decided how frequently to sample items: e.g. one could sample every third item or every fifth item. Let k represent the sampling frequency. to begin the sampling, choose a starting place at random. Select the item in the starting place, along with every nth item after that. sometimes used in assembly lines in order to check that they meet quality standards

Question 11

voluntary response

Answer 11

often used by the media to try to engage the audience. ex: a news commentator will invite people to tweet an opinion, or a radio announcer will invite people to call the station to say what they think. they are never reliable and people who go to the trouble to volunteer an opinion tend to have stronger opinions than is typical of the population. Additionally, people with negative opinions are often more likely to volunteer their responses than those with positive opinions.