Chapter 5 ~ Producing Data

Question 1

observational study

Answer 1

observes individuals and measures variables of interest but does not attempt to influence the response

Question 2

experiment

Answer 2

deliberately imposes some treatment on individuals in order to observe their responses. An experiment can help eliminate (or at least try to minimise the effects of) lurking variables.

Question 3

population

Answer 3

the entire group of individuals that we want information about

Question 4

sample

Answer 4

the part of the population which we actually examine in order to gather info

Question 5

sampling

Answer 5

studying a part in order to gain information about the whole

Question 6

census

Answer 6

attempts to contact every individual in the entire population

Question 7

voluntary response sample

Answer 7

consists of people who choose to be part of a sample by responding to a general appeal
biased

Question 8

convenience sample

Answer 8

involves choosing the most convenient individuals from the population for your sample
biased

Question 9

simple random sample (SRS)

Answer 9

a sample of size n is selected in such a way if every individual in the population has an equal chance of being selected and every subset of n individuals has an equal chance of being selected for the sample

Question 10

stratified random sample

Answer 10

includes the following steps: divide the population into groups of similar individuals called strata, choose a separate SRS from each stratum, and then combine all of those individuals chosen from all of the strata to make up the full sample.
NOT an SRS

Question 11

cluster sample

Answer 11

divides the population into groups (or clusters), then randomly selects some of these clusters (completely ignoring the others). All of the individuals from the chosen clusters are selected to be in the sample.

Question 12

multistage sample design

Answer 12

selects successively smaller groups within the population in stages, resulting in a sample consisting of clusters of individuals. Each stage may employ an SRS

Question 13

systematic sample

Answer 13

choosing every nth unit for the sample for some positive integer n.
ex: suppose you want to inspect packages of potato chips coming off the Lays factory assembly line. A systematic sample would involve inspecting, for example, every 25th bag coming off the line.

Question 14

probability sample

Answer 14

gives each member of the population a known chance to be selected

Question 15

undercoverage

Answer 15

occurs when some groups in the population are left out of the process of choosing the sample

Question 16

nonresponse

Answer 16

occurs when an individual chosen for the sample cannot be contacted or refuses to cooperate

Question 17

response bias

Answer 17

occurs when an individual in a sample chooses an answer to a survey that he/she thinks is best rather than the answer that he/she truly believes

Question 18

wording of question

Answer 18

may influence a person by leading the individual being questioned to one answer as opposed to another

Question 19

experimental units

Answer 19

individuals on which the experiment is being done

Question 20

subjects

Answer 20

experimental units that are people

Question 21

treatment

Answer 21

the specific experimental condition applied to the units. The level of treatment is measured by the explanatory variable and the level of the variable we’re interested in is measured by the response variable.

Question 22

factors

Answer 22

the explanatory variables in an experiment (i.e. the changes that are being imposed on the subjects in the experiment). Experiments may have several factors.

Question 23

3 Principles of Experimental Design

Answer 23

CONTROL the effect of lurking variables on the response variable
RANDOMIZATION ensures that individuals are assigned to treatment groups by chance
REPLICATION of the experiments many times or on many subjects ensures that the results are not just due to chance variation

Question 24

randomized comparative experiment

Answer 24

an experiment that has random assignment and a control or comparison group

Question 25

statistically significant

Answer 25

an observed effect too large to attribute plausibly to chance

Question 26

placebo effect

Answer 26

occurs when a subject receiving a placebo reacts favourably to it

Question 27

block

Answer 27

a group of experimental units or subjects that are known before the experiment to be similar in some way that is expected to affect the response to the treatments. In a block design, the random assignment of units to treatments is carried out separately within each block. THE ASSIGNMENT OF SUBJECTS TO BLOCKS IS NOT RANDOM.

Question 28

homogeneous group

Answer 28

another name for a block

Question 29

matched pairs design

Answer 29

a special type of block design in which ONE of the two conditions is satisfied:

1) subjects are matched with themselves and given two different treatments (in a random order). This is the more commonly used form of matched pairs design.
2) similar subjects are matched and each assigned a different treatment.

Question 30

blind experiment

Answer 30

the subjects involved in the study do not know which treatment that are receiving

Question 31

double-blind experiment

Answer 31

neither the researches nor the subjects know who is receiving which treatment.
(the experimenters are aware)

Question 32

researcher

Answer 32

the person measuring the response variable

Question 33

experimenters

Answer 33

the people running the overall experiment, and are aware of who is receiving which treatment

Question 34

lack of realism

Answer 34

serious potential weakness of experiments