Chapter 7

Question 1

Nonprobability sampling

Answer 1

Sample elements are chosen non randomly.
Produces biased sample
Each element of the population may not be included in the sample.
Restricts generalizations made about study findings

Types
Convenience: The most common type of sampling. A non probability method of selecting a sample that includes subjects who are available in a convenient way to the researcher.
Quota: a number standard
Purposive: specific to characteristics of the study
Snowball Sampling: word of mouth

Question 2

Nonprobability Sampling Procedures Advantages/Disadvantages

Answer 2

Advantages
Time
Money

Disadvantages
Nonrandom
Not able to generalize findings

Question 3

Sampling frame

Answer 3

Members of the population who are available and accessible to the researcher

Question 4

Representativeness

Answer 4

Members of the sample are similar to the population in major characteristics of interest

Question 5

Sampling error

Answer 5

Differences between the sample and the population that are due to the way the sample was drawn

Question 6

Selection bias

Answer 6

Differences between the sample and the population that are due to manipulation by the researcher

Question 7

Inclusion criteria

Answer 7

Objective attributes that are necessary
Clinical
Demographic
Geographic
Temporal

Question 8

Exclusion criteria

Answer 8

Attributes that may affect the outcome
Co-morbid conditions
Behavioral (high potential for attrition)

Question 9

Probability Sampling

Answer 9

A sampling process used in quantitative research in which every member of the available population has an equal probability of being selected for the sample.

Allows researcher to estimate the chance
Helps with inferential statistics (quantitative) with greater confidence
Gives the ability to generalize the findings
Allows researcher to estimate the chance

Question 10

Probability Sampling Types

Answer 10

Simple random: name out of hat
Stratified random
Cluster random: limited sample size
Systematic random: pick every 10th person

Question 11

Simple Random Sampling (probability)

Answer 11

Type of probability sampling

Importance of this sampling:
Equal chance of selection
Independent chance of selection
Time consuming

Question 12

Advantages of Simple Random Sampling

Answer 12

Little knowledge of population is needed.
Most unbiased of probability method
Easy to analyze data and compute errors

Advantages of Simple Random Sampling
Complete listing of population is necessary.
It is time consuming to use.

Question 13

Stratified Random Sampling

Answer 13

Type of probability sampling
Population is divided into subgroups or strata.
Strengthens probability/control for participants
Simple random sample taken from each strata

Advantages
Increases probability of being representative
Ensures adequate number of cases for strata

Disadvantages
Requires accurate knowledge of population
May be costly to prepare stratified lists
Statistics are more complicated

Question 14

Cluster Random Stratified Sampling

Answer 14

Large groups or clusters (to a characteristic), not people, are selected from population.

Simple, stratified or systematic random sampling may be used during each phase of sampling.

Advantages
Saves time and money
Arrangements made with small number sampling units
Characteristics of clusters or population can be estimated.

Disadvantages
Causes a larger sampling error
Requires each member assignment of population to cluster
Uses a more complicated statistic analysis

Question 15

Systematic Random Sampling

Answer 15

Type of probability sampling
Every kth element is selected.

Advantages
Easy to draw sample
Economical
Time-saving technique

Disadvantages
Samples may be biased.
After first sample is chosen, no longer equal chance

Question 16

Qualitative Sampling

Answer 16

Purposeful method
Primary concern: ability to inform the question
Researcher often involved in recruitment and selection
Criteria may be used for inclusion and exclusion

Redundancy and Saturation
When is the point at which no new information is being generated?

Question 17

Factors affecting power analysis

Answer 17

Biggest effect: sample size
Level of accuracy required
Number of variables to be studied
Variability in the population
Magnitude of effect
Independence of the data

Question 18

Power analysis

Answer 18

Helps to determine sample size
May prevent type II error
Helps to detect statistical significance
Low power; type II error high
External funding sources require it.
Helps determine the optimum sample size

Question 19

Population

Answer 19

Entire set of subjects that are of interest to the reader
Common characteristic
Of interest to the researcher

Question 20

Sample

Answer 20

Subset of the population

Sample represents the population characteristics

Question 21

Target Population

Answer 21

Entire group of people or objects
People or objects meet designated set of criteria.
Generalization of the findings

Accessible Population
Group of people or objects
Researcher has access to them.

Question 22

Sampling Concepts/Stratigies

Answer 22

Sampling Frame
Respresentativeness
Sampling error
Selection Bias

Question 23

Convenience Sampling Advantages/Disadvantages

Answer 23

Advantages
Expedited data collection
COST-EFFECTIVE
Easy sampling
Ready availability for data

Disadvantages
Biased
Outliers
Insufficient power