Chapter 10 - Sampling & Data Collection in Quantitative Studies

Question 1

What is the population?

Answer 1

The entire group of interest

The collection of elements/cases in which a researcher is interested in

Question 2

What is a sample?

Answer 2

a section of a portion of the population to represent the entire population

A subset of population elements→ elements are usually humans

Question 3

What is eligibility criteria? Inclusion vs. exclusion criteria

Answer 3

specific characteristics to define the population

Inclusion criteria: characteristics that make one a member of the population

Exclusion criteria: characteristics that cause one to be excluded from population

Question 4

Target population

Answer 4

the entire population in which a researcher is interested (ex. all diabetics in the US)

Question 5

Accessible population

Answer 5

portion of the target population that is accessible to the researcher (ex. all diabetics at one hospital)

Question 6

Strata

Answer 6

mutually exclusive segments of a population based on specific characteristics
(Ex. RNs in the UK can be separated by GENDER, Years of experience)
–> Strata are often used in sample selection to enhance the samples representativeness

Question 7

Representative Sample

Answer 7

one whose characteristics closely approximate those of the population

Question 8

Sampling Bias

Answer 8

systematic overrepresentation or underrepresentation of some segment of the population in terms of key characteristics when the sample is not representative
–>can be risky to apply it to the population because it could be very incorrect

Question 9

A representative sample is most easily achieved with… (3 things)

Answer 9

1. Probability sampling – sampling at random
2. Homogenous populations – more alike than different
3. Larger samples – people in sample are more likely to have the characteristics you are looking for

Question 10

Nonprobability Sampling

Answer 10

researchers select elements by nonrandom methods in which every element usually does not have a chance to be included

• rarely produce representative samples
• MOST research samples in nursing are nonprobability

Question 11

Convenience Sampling

Answer 11

selecting the most conveniently available people as participants
-problem: atypical population, bias –> weakest form of sampling

Question 12

Quota Sampling

Answer 12

identify population strata and figure out how many people are needed from each stratum –> ensures diverse segments are accurately represented

-participants are a “convenience sample” from each stratum

Question 13

Consecutive Sampling

Answer 13

recruiting ALL people from an accessible population over a specific time interval or for a specified sample size

• longer sample time = less bias due to seasonal fluctuations
• best choice when their is “rolling enrollment” in population

–>ex. ICU patients admitted over 6 months, or the first 250 patients

Question 14

Purposive Sampling

Answer 14

based on the belief that researchers’ knowledge about he population can be used to hand-pick sample members

• can lead to bias (based on purposeful judgement of the researcher)
• useful when you want a sample of experts
• mostly qualitative

Question 15

Probability Sampling

Answer 15

involves random selection of elements form a population - all elements have equal chance of being selected

• random sampling
• only viable method of obtaining representative samples, can easily estimate sampling errors (ex. average age of population) and sample values (ex. average age of the sample)
• often impractical

Question 16

Random Sampling

Answer 16

• used on probability sampling

- ->each element in the population has an equal, independent chance of being selected

Question 17

Simple Random Sampling

Answer 17

most basic probability sampling

• researchers establish a sampling frame (list of population elements –> ex. student roster for sampling students at MU, pulling names out of a jar)
• no guarantee of a representative sample, but there is no researcher bias (sample of CHANCE)

Question 18

Stratified Random Sampling

Answer 18

population is first divided into two or more strata, from which elements are randomly selected

• ->ex. sex, ethnicity
• aim to enhance representativeness
• only works if stratifying variable is available

Question 19

Systematic Sampling

Answer 19

selection of every “kth” case from a list (ex. every 10th person on a patient list)
-divide population into sampling interval and then select sample from different intervals

Question 20

Sample Size

Answer 20

the number of study participants in the final sample
LARGER is better = less sampling error
-Sample size adequacy needed for quantitative research

Question 21

Power analysis

Answer 21

helpful in estimating how large their samples should be for testing their research hypothesis
–>when predicted differences are small - a large sample is needed

Question 22

What are the two issues to assess when critiquing a sampling plan?

Answer 22

1. Has the researcher adequately described the sampling strategy?
2. Has the researcher made good sampling decisions?

Question 23

Ideal description of the sampling strategy

Answer 23

• The type of sampling approach used
• The population under study and eligibility criteria for sample selection
• The sample size, with a rationale
• A description of the samples main characteristic (age, gender, clinical status)
• The number and characteristics of potential subjects who declined to participate

Question 24

How do you know if the researcher has made good sampling decisions?

Answer 24

1. Response rates: the number of people who participated in a study relative to the number of people sampled
2. Nonresponse bias: differences between participants and those who declined to participate (response bias)
   - ->In longitudinal studies attrition (dropping out) bias should be reported

Question 25

Data Collection: New data vs. old data

Answer 25

New data – data collected specifically for research purposes (primary data) Existing data – records, historical data, existing data sets (secondary analysis)

Question 26

Self-Report

Answer 26

participants' responses to questions posed by the researcher - ->best when researchers know in advance exactly what they need to know and can frame appropriate questions needed to obtain needing information - most common in nursing studies - direct observation may be used

Question 27

Closed-ended questions

Answer 27

response alternative are prespecified (ex. yes or no) - good closed ended questions are difficult to construct but easier to analyze, more efficient - may be superficial

Question 28

Advantages of Questionnaires

Answer 28

- less costly - can be dispersed anywhere easily (especially over internet) - possibility of anonymity

Question 29

Advantages of Interviews

Answer 29

* more than questionnaires - response rates are higher (don't refuse to talk to an interviewer as much) - interviews are feasible with most people (many cannot fill out a questionnaire - children, blind, elderly) - interviewers can produce additional info through observation of responders behavior/living situation

Question 30

What is a scale?

Answer 30

a device that assign a numeric score to people along a continuum (ex. scale for measuring weight) -->social-psychological scales quantitatively discriminate among people with different attitudes, perceptions, and psychological traits

Question 31

Likert Scale

Answer 31

several declarative statements (items) that express a viewpoint on a topic -->express how much you agree or disagree with a statement Summated Rating/Composite Scale: sum of item scores

Question 32

Visual Analog Scale (VAS)

Answer 32

used to measure subjective experiences (ex. pain, dyspnea) - a straight line with end anchors that are labeled as the most extreme limits (no pain vs. worst pain ever) - should be 100 mm in length = score of 0-100

Question 33

Social Desirability Response Set Bias

Answer 33

a tendency to misrepresent attitudes or traits by giving answers that are consistent with prevailing social views

Question 34

Extreme Response Set Bias

Answer 34

a tendency to consistently express extreme attitudes or feelings (ex. strongly agree) leading to distortions because extreme responses may be unrelated to trait being measured

Question 35

Acquiescence Response Set Bias

Answer 35

a tendency to agree with statements regardless of their content by some people (yea-sayers) or disagree with statements independent of the question's content (nay-sayers)

Question 36

What areas do observational researchers have flexibility?

Answer 36

1. Focus of observation - broad (events) or narrow (specific behaviors - facial expressions) 2. Concealment - may not tell subjects they are observing (reactivity: behavior distortions because they know they are being watched) 3. Method of recording observations - paper and pencil recording or sophisticated methods (ex. video, audio, computers)

Question 37

Category System

Answer 37

represents a method of recording in a systematic fashion the behaviors and events of interest that transpire within setting Non-exhaustive: all observed behaviors are classified into one category Exhaustive: many behaviors in many categories

Question 38

Rating scale

Answer 38

observers rating phenomena along a descriptive continuum (occurrence + qualitative aspect of it)

Question 39

Time sampling vs. event sampling

Answer 39

Time Sampling: selection of time periods during which observations will occur (ex. every 20 seconds at 2 min intervals) Event Sampling: selection of integral behaviors/events to observe, more for infrequent events

Question 40

Biophysiologic Measures

Answer 40

--> used for wide variety of purposes: basic biophysiologic processes, exploring ways in which nursing actions/interventions affect physiologic outcomes, product assessments, etc In Vivo: performed directly within or on living organisms (ex. BP, temp) In Vitro: gathered b extracting biophysiologic material from them and analyzing it (ex. hormone levels, bacterial counts, tissue biopsies)

Question 41

Advantages of Biophysiologic Measures

Answer 41

- relatively accurate/precise - objective (two nurses would read same BP on monitor/two monitors would read the same) - pts cannot easily distort measurements - provide valid measures of targeted measures (thermometers measure temperature, not blood volume)

Question 42

Semantic Differential Scale

Answer 42

• Continuum between 2 adjectives • Continuum varies from 5 to 9 Ex. My nurse is.. MEAN -------------------NICE