intro to data collection

Question 1

observational study

Answer 1

data collected only by monitoring
researchers collect data on individuals in a way that doesn’t directly interfere with how the data arises and doesn’t attempt to influence the responses

cannot make causal conclusions on them

Question 2

experimental study

Answer 2

researchers directly influence the process by which the data arises, usually involving the assigning of participants to one or more treatments

can make causal conclusions on them

Question 3

what is the best way to ensure a sample is representative of the population where it came from

Answer 3

to ensure that all the observations that comprise it were selected randomly

Question 4

explanatory and response variables

Answer 4

explanatory variables are the independent variables that might affect or give rise to the response variable/ dependent variable

Question 5

sampling design

Answer 5

describes exactly how the sample is chosen from the population

Question 6

what do good sampling designs allow us to do

Answer 6

generalize from the sample to the population
(make an inference about the population from the sample data)

Question 7

simple random sampling

Answer 7

a sample where each possible sample of size n has the same chance of being the sample that is selected

every member in the population has an equal chance of being included and there is no implied connection between members in the sample

Question 8

stratified sampling

Answer 8

population is divided into non overlapping groups called strata

works best when there’s is a lot of variability between each stratum, but no much variability within each stratum

division of individuals into groups of similar interests

Question 9

multistage sampling

Answer 9

involves taking simpler samples within simple random samples
big sample, smaller sample, even smaller sample
some subgroups are oversampled to ensure representation in the sample

Question 10

bad sampling examples

Answer 10

a convenience sample —> obtained by measuring whatever or whoever is available to be measured

voluntary response sample —> individuals decide whether to participate in study

Question 11

what survey challenges result from bad sampling?

Answer 11

1. undercoverage : leaves out some groups in the population
2. no response: individuals who are selected in sample can’t be contacted or refuse to participate
3. response bias : participants respond differently from how they truly feel

Question 12

confounding variable

Answer 12

variables associated with both the explanatory and response variable

get in the way of being able to make causal conclusions about the relationship between the two variables

provide an alternative explanation for why response occurs

^^ reason why we cant make causal statements from observational studies

Question 13

randomized controlled experiment

Answer 13

includes comparison of 2 or more treatments
uses interpersonal chance of participants to the treatment ( random assignment)

Question 14

single blind

Answer 14

when the participants font’ knwo which group they are in

Question 15

double blind

Answer 15

when reasearchers also font know which participants are in which group so they control for researcher expectation

Question 16

block designs/ blocks

Answer 16

control the effects of some outside variables by bringing those variables into the experiment to form the blocks

block: group of individuals known before the experiment to be similar in some way that is expected to affect the response to treatments

block design: random assignment of individuals to treatments is carried out separately within each block