Unit 4 Flashcards
What is the major goal of research?
To gain information about different variables
When is a sample representative?
when it’s a good reflection of a wider population
-> results can be generalised
What are the factors that make a sample representative?
Suitability
Sample size Accessibility
Suitability
Inclusion and exclusion criteria based on demographic characteristics
Participant characteristics
major demographic characteristics
important top-specific characteristics (e.g. acheivement level in studies)
H0
Null Hypothesis
No difference between groups
H1
Alternative hypothesis
difference between groups
Why is sample size essential for the research design?
Increase in sample size -> increase in power
-> increases probability of rejecting null hypothesis
Are sample size and power linearly related?
No
-> too small ->low probability of rejecting null hypothesis
-> too large -> unnecessarily increases cost
=> after 90% slow increase in power for increasing sample size
Power
probability of correctly rejecting null hypothesis
doesnt statistically differ between study groups
What are accessibility sampling procedures useful for?
to describe:
- procedures for selecting participants
- setting and location of data collection
- agreements and payments to participants
- institutional review board agreements, ethical standards met, safety monitoring
Probability sampling
each population element has known chance of being chosen (above 0)
Non-probability samples
researcher can’t specify probabilities
What does probability sampling require?
a sampling frame
-> list of all members of population
Subtypes of probability sampling
Simple random sampling
Systematic sampling
Cluster sampling
Stratified sampling
Simple random sampling
Properties:
- population of N objects included in sampling frame
- sample of n objects
- all possible samples of n equally likely
Systematic sampling
list of population created
every kth member selected
-> e.g. every 3rd person
Cluster sampling
every member of a population assigned to one group (cluster)
one cluster used as sample (selected via other probability method)
only individuals within cluster surveyed
doesnt require sampling frame
stratified sampling
population divided into strata (groups)
within each group probability sample selected
What’s the difference between cluster sampling and stratified sampling?
Stratified sampling: includes elements fro. each stratum
Cluster sampling: only elements from sampled cluster
Subtypes of non-probability samples
Judgemental sampling
Convenience sampling
Quota sampling
Judgemental sampling
Sample members chosen based on researchers knowledge and judgement
-> chances that results will be highly accurate with minimal margin of error
Convenience sampling
made from people of are easy to reach and willing to participate
Quota sampling
Individuals chosen according to specific characteristics or traits
care taken to maintain correct proportion representative of population
(e.g. 45% male, 55% female)
What is data collection?
Process of gathering and measuring information on variables of interest in established systematic fashion
allows to answer stated research question
What are different types of survey techniques?
Interviews
Questionnaires
What is the survey method important for?
to study relationships among variables and ways that attitudes and behaviours change over time
Which potential issue do we face in surveys?
different biases
What is the most common bias?
social desirability bias (aka “faking good”)
Social desirability bias
participants answer in most socially accepted way
-> underreport undesirable behaviours
-> overreport positive behaviours
Interview
asking questions and getting answers
forms: individual face to face; face to face group interviews
What are the advantages of interviews?
Carried out by trained researcher
Involves social interaction
Collecting information
What are the disadvantages of interviews?
high costs
small samples
Types of interviews
structured: wording, content and sequence of questions prepared
semi-structured: writing, content and sequence of question structured modifiable
unstructured: a few broad questions -> open, informal and spontaneous discussion
Types of questions
closed questions: fixed set of responses
open questions: express thoughts in own words
Questionnaires
research instrument consisting of series of questions to gather information
What is measured in questionnaires?
latent traits (e.g. personality traits)
health component (e.g. sleep, mood)
attitudes (e.g. towards immigration)
index (e.g. social status)
preferences (e.g. political party)
behaviours (e.g. food consumption)
facts (e.g. gender)
How are closed questions coded?
In likert scale
-> responses coded along range measuring positive or negative response
forced choice questions
makes survey respondents choose option idicating definitive opinion
Strengths of quesstionnaires
completed by participant
easily applied
large samples
Weaknesses of questionnaires
low response rates
misunderstandings
random responses
open-ended questions
require elaboration on points
mixed questionnaires
closed and open-ended questions
Observation
Greater objectivity than surveys
Data collected on observable behaviours
more complicated
variables operated as observable behaviours
What is a potential risk during observations?
people may change behaviours if observed
What do observations require
Period of habituation
Careful participant observation
Objectivity of observer
Index of observations
Recording of sequence
What is a performance test?
Index requiring examinee to perform task
-> ensures greater fidelity
Key features of performance tests
control over variables
careful measurement
establishing cause-effect relationship
What does psychometrics focus on?
measuring one’s cognitive abilities
What are performance psychometrics?
standardised measures of particular psychological variables
Internal structure of performance tests
One-dimensional: measures single factor and gives total score
Multidimensional: measures several factors, gives several scores
What is Cronbach’s alpha?
measure of internal consistency
measure of scale reliability
