Studied by 58 people

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1

census

a procedure by which EVERY MEMBER of a population is selected for study

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2

representative sample

a sample w/ the essential characteristics of the population studied without any bias

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3

sampling frame

list of all the members of population from which we can draw a sample

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4

probability sample

a sample in which every individual in the population has a known probability of being sampled

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5

simple random sample

a sample in which ALL samples of size x have an equal probability of being drawn

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6

systematic sample

a sample in which the starting point is chosen randomly, but afterwards the sample is drawn from some predetermined system/pattern (e.g. every 12th person)

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7

stratified sample

sampling frame is divided into homogeneous groups, then random sample is drawn from each homogeneous group

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8

cluster sample

sampling frame is divided into groups which are all the same/intended to be representative of the population; then, clusters are sampled randomly

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9

self-selected/voluntary response sample

a sample in which people choose whether or not to participate in the survey/respond (TENDS TO BE BIASED, VOLUNTARY RESPONSE BIAS)

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10

convenience sample

sample drawn however is most convenient (TENDS TO BE BIASED)

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11

quota sampling

individuals are selected intentionally to try to reflect different quotas of groups in the population, e.g. selecting x amount of teens to include because teens make up y proportion of the population (TENDS TO BE BIASED)

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12

bias

the tendency of a sample statistic to systematically over- or under-estimate a population parameter (e.g. our sampling method will regularly & systematically produce samples that misrepresent our data in the same way)

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13

undercoverage

one part of the population being sampled is excluded/underrepresented

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14

voluntary response bias/nonresponse bias

certain individuals (those who feel certain ways about the subject matter of the survey) will choose not to respond/to respond; the groups of individuals who respond/don’t respond are the same w/ respect to the variable of interest & thus we’ve under/overrepresented a group in our population

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15

wording bias

bias which occurs when the wording of the question(s) being asked influences the responses in a SYSTEMATIC way

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16

what are some situations in which we might see response bias?

the respondent might not want to give a truthful answer to the question (e.g. income questions); the respondent might not UNDERSTAND the question (ambiguous wording); the respondent might want to please the interviewer; the order in which options were listed might influence the answers of the respondent; etc.

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17

a difference between treatment results/treatment & no treatment results is statistically significant if…

this difference is too large to attribute to chance/natural random variation

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18

experiment

a study in which researchers ASSIGN individuals to treatments/impose treatments on individuals

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19

observational study

a study in which researchers observe individuals and record data but DON’T impose treatments

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20

retrospective studies study what is in the ____; prospective studies will study events in the…

past; future

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21

confounding variable

a variable that has an effect on the outcomes of the study but whose effects can’t be separated from those of the treatment variable

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22

statistical control

a situation in which all variables other than the one of interest are HELD CONSTANT across all treatment groups

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23

what are the 3 basic principles all experiments must incorporate?

randomization, replication, and control

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24

randomization is done to…

equalize groups so that the effects of extraneous variables are equally distributed among groups

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25

replication is done to…

minimize effects of random chance on our results (e.g. ensure differences between results for our groups aren’t due to random extremity)

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26

control is enforced to…

minimize confounding; ensure groups only differ with respect to variable of interest

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27

completely randomized design

subjects randomly assigned to treatment groups, treated; effects of treatments compared

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28

placebo

an inactive treatment used when effects of treatment are compared to effects of no treatment (placebo only used for HUMAN subjects)

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29

blinding

preventing a party in the experiment from knowing which treatment they received (single blind: either subject or evaluator doesn’t know; double blind: both subject and evaluator don’t know)

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30

when describing a method of randomization, be sure to…

specify method of randomization, specify whether sampling w/ or w/out replacement, and (if using random digits table) specify what represents 1 [e.g. 01 is 1]

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31

randomized block design

completely randomized experiment is performed WITHIN each block, results compared WITHIN blocks

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32

matched-pairs design

two subjects similar to each other are paired, becoming a block, or one person becomes a pair & their before/after results are compared

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