week 5

Question 1

define sampling

Answer 1

A process by which a subgroup of participants is selected for study from a larger group of potential participants

Question 2

importance of sampling

Answer 2

Essential to research:
- Suitable to research design
- Carefully selected
↑Generalisability / External validity

Question 3

difference between population and sample

Answer 3

population= total group of interest
samples= subgroups of the total group of interest eg elderly

Question 4

whats random bias

Answer 4

happens by chance

Question 5

WHATS SYSTEMATIC BIAS

Answer 5

• Volunteers
• Non-respondents
• People that share some common characteristics
• People with a vested interest in project

Question 6

issues affecting sampling

Answer 6

• Study questions / hypotheses
• Research approach: Quantitative, Qualitative, Single-case design
• Practical considerations: Availability, Time, Space, Budget, Personnel…
• Other issues: Gender, Race, Age, Location, Socio-economic level, Culture, Language, Education level, Religious issues, Vulnerability Level

Question 7

four steps to sampling

Answer 7

Step 1: define the population of interest
Step 2: consider the unit of analysis individuals (usually), families, facilities, areas, cultures
Step 3: develop a sampling plan method, where, time, sample size, type and description
Step 4: implement sampling procedures

Question 8

sampling techniques

Answer 8

• Volunteers / convenience sampling
• Targeted recruitment
• Inducement / payment / compensation
• Randomised: simple / stratified
• Purposive
• Snowball / networking

Question 9

whats sample requirement quant

Answer 9

• Representative
• Specify inclusion & exclusion criteria
• Establish minimum number of participants required

Question 10

whats probability sampling

Answer 10

• Each person can theoretically have an equal chance of being selected for the sample
• Population is known
• Reduces sampling biases / increases study rigor

Question 11

types of probability sampling

Answer 11

1. Simple random sampling
   - Sampling without replacement
   - Manual methods: draw names out of hat
   - Random tables or computer-generated lists
   - Use computer randomisation assignment programs
2. Stratified random sampling
   - Selection from identified subgroups
3. Systematic random sampling
   - Selection from every nth Person on a list
4. Cluster sampling
   - Not randomly select individual participants • Select groups or programs

Question 12

whats non probability sampling

Answer 12

• Population is unknown

- Not feasible to use probability sampling

Question 13

types of non probability sampling

Answer 13

Convenience: Volunteers or easily available participants
Purposive: Deliberate selection & recruitment by researchers
Snowball or Networking: When potential participants are difficult to obtain
Quota: When different proportions of participants are needed based on specific criteria (e.g., gender, age, diagnosis, education level)

Question 14

when is non probability sampling used

Answer 14

When non-probability sampling is used…

• Clearly define the process of the sampling
• Acknowledge the limitation of the sampling procedure used
• Justify if the sampling limitations do harm the research question being answered

Question 15

sampling in quant

Answer 15

Larger sample size = better generalisation 
General rules of thumb 
- general rules of thumb
- statisitcal power
- effect size
- level of significance
- power

Question 16

whats general rule of thumb quant

Answer 16

• 30 participants is a minimum number to complete correlation research (Note for your OCC3041 survey assignment you are only being asked to recruit in the region of 10-12 participants)
• 100 participants for survey research
• 20-50 in each minor subgroup
• 15 participants for causal-comparative research

Question 17

statistical power quant

Answer 17

• The likelihood of finding a significant difference between groups or correlation between variables when one truly exists
  1. Sample size
  2. Effective size
  3. Level of significance
  4. Power

Question 18

whats is effect size

Answer 18

• “the effect of difference between 2 means or the degree of correlation between 2 variables in the results of a study”
• Effect size↓, Sample size↑

Question 19

whats level of significance

Answer 19

• The probability that the investigators will find an effect by chance when there really is no true effect
• Probability statistic is referred to as p-value
• P-value of 0.05 (e.g., 5% of something occurring due to chance) is the standard level used in most studies
• Some studies use p-value of 0.01 (if they want to raise the bar on the degree of significance or rigor required!)

Question 20

whats power

Answer 20

• Calculation completed to determine the minimum sample size required to complete a study
• 0.8 usually in occupational therapy studies

Question 21

two principles of sampling in Qual

Answer 21

1. Appropriateness
   - Identification of participants who will best inform the research about the phenomena under inquiry
2. Adequacy
   - Enough data will be available to provide a rich description of the phenomena of interest
   - Continue to collect data until data saturation is reached or data source is exhausted (diminishing returns)

Question 22

strategies of sampling qual

Answer 22

• Purposeful selection
• Maximum variation
• Individuals who have different experiences
• Homogenous
• Individuals who have the same experiences
• Theory-based selection
• Convenience selection
• Snowball or network selection (some one who knows someone who knows some one etc)

Question 23

six types of sampling qual

Answer 23

Purposeful sampling: 
Convenience sampling: 
Theoretical sampling 
Maximum variation sampling:
Homogeneous sampling Snowball sampling

Question 24

whats purposeful sampling

Answer 24

Information rich cases (individuals, settings or cases) that poses indepth knowledge and experience of research topic

Question 25

whats convenience sampling

Answer 25

Participants are conveniently available and willing to participate – Useful when participants who meet specific criteria are difficult to find

Question 26

what theoretical sampling

Answer 26

Sampling approach used in grounded theory research design | – Researcher seeks people, events or information to refine theoretical categories emerging from the data

Question 27

whats Maximum variation sampling

Answer 27

– Heterogeneous (diverse) sample of participants selected based on a range of characteristics – Focuses on exploring diversity and capturing breadth in relation to research topic – For example: university student, sampling characteristics might include: type of university degree, levels of study, gender, ethnicity, social class

Question 28

Homogeneous sampling

Answer 28

– Selecting participants who are as similar as possible, narrowing to specific group of participants – Useful when resources are limited and to understand research topic in-depth – For example: e.g. female year 1 OT students

Question 29

Snowball sampling

Answer 29

– Existing participants suggest new participants who meet study purpose & inclusion criteria (word of mouth)

Question 30

Outline strategies used to determine sample size in qualitative research

Answer 30

- No set sample size or formula to determine sample size - Sample for meaning rather than frequency, number or size - Sampling process is flexible, with number of participants not definitely known at the start of a study - Sample is adequate when emerging themes are well developed & no new information comes from further data collection - Data saturation – sample until redundancy of ideas emerge

Question 31

subject pool

Answer 31

those who are identified as eligible to participate in the study.

Question 32

statistical power

Answer 32

the likelihood of finding a significant difference between grops or association between variables when one exists.

Question 33

Securing samples and performing sites Anne E dickersons chapter 15 Five critical steps of sampling:

Answer 33

1. Define the population of interest 2. Consider the unit of analysis 3. Identify a performance sit 4. Develop a sampling approach 5. Impalement the sampling procedures

Question 34

whats appropriateness in qual

Answer 34

the identification of participants who will best inform the researcher about the phenomena under inquiry

Question 35

whats sample frame

Answer 35

: the set of people that has a chance to be selected given the sampling approach that is chosen