Non-probability sampling: researchers select people into the study by non-random methods, and not
everyone has the same chance to be included.
o
Convenience sampling: selecting the most conveniently available people as participants.
Weakest form of sampling, risk of bias.
o
Quota sampling: researchers identify population strata and figure out how many people are
needed from each stratum.
o
Consecutive sampling: recruiting all people from an accessible population over a specific time
interval or for a specified sample size.
o
Purposive sampling: using researchers’ knowledge about the population to handpick sample
members.
Probability sampling: random selection of elements from a population. Each element has an equal,
independent chance of being selected.
o
Simple random sampling: most basic probability sampling. Researchers establish a sampling
frame.
o
Stratified random sampling: population is divided into 2 or more strata from which elements are
randomly selected.
o
Systematic sampling: involves the selection of every x
TH
case from a list. Ex: every 10
TH
person on
the list is selected.
Sample size: number of participants. Larger is usually better.
Power analysis: researchers estimate how large their samples should be for testing hypotheses.
Critiquing sampling plans:
o
Type of sampling approach used (convenience, consecutive, random)
o
Population and eligibility criteria from sample selection
o
Sample size, with a rationale
o
Description of the sample’s main characteristics (age, gender, clinical status, etc)
Data collection in quantitative research
Self-report data/ Patient-reported outcome (PRO): participants responses to researchers’ questions
(ex: interview). Most common data collection approach in nursing.
o
Interview schedule: when questions are asked orally face-to-face or by telephone.
o
Open/closed ended questions.
o
Interviews vs questionnaires: Questionnaires = less costly, advantageous geographically,
economical, autonomity. Interviews = response rates are higher when face-to-face, less likely to
reuse to talk, feasible.
o
Scale: device that assigns a numeric score to people along a continuum
Observational methods: used to gather information as patients’ conditions, verbal communication,
non-verbal communication, activities, and environmental conditions.
o
Category system: records events of interest that happen within a setting systematically.
Biophysiologic measures:
Reliability: extent to which are free from measurement error.
Test-retest reliability: replication takes the form of administering a measure to the same people on 2
occasions.
Validity: the degree that an instrument is actually measuring the construct it supposes to measure.
o
Face validity: whether the instrument looks like it is measuring the target construct
o
Content validity: the extent that an instrument’s content adequately captures the construct
o
Criterion validity: extent to which the scores on a measure are a replication of a gold standard.
