participant recruitment and sampling

steps in sampling

1. define the population of interest 2. consider the unit of analysis 3. identify a performance site 4. develop a sampling approach 5. implement the sampling procedures

4 components of power analysis

1. sample size 2. statistical power (the likelihood the finding of statistical significance actually exists-- the mini acceptable level is .8 3. effect size (the magnitude of statistical significance) 4. level of significance (typically set at .05); (when three of the components are known, the fourth one can be calculated)

Systematic sampling (probability sampling)

Considered equivalent to random sampling as long as there is no reoccurring pattern of order in the listing-- the number of subjects for the sample is known and divided into the number of the population

Purposive sampling (non-probability sampling)

Deliberate selection of individuals by the researcher based on certain predetermined criteria (usually stated as inclusion and exclusion criteria)

Convenience sampling (non-probability sampling)

Most problematic, yet widely used. The use of volunteers or easily available subjects such as a group of students in a program or clientele in a clinic

everyday philosophers,

Those who think a great deal about the setting and can give insight to what is going on, but they are not as forthcoming with their ideas

Quota sampling (non-probability sampling)

Used when different proportions of subject types are needed so that there is appropriate representation in the sample that may not be attainable with purposive or convenience sampling

systematic errors

a flaw and serious problem- sources of this error include using volunteers and using groups that are available and convenient

secondary selection

a strategy a qualitative researcher may use when he or she does not know who the best participants are

Simple random sampling (probability sampling)

all individuals in a defined target population have an equal and independent chance of being selected for a sample

Stratified random sampling (probability sampling)

all individuals in identified subgroups of the population have an equal and independent chance of being selected for a sample

sampling errors

differences bw the study sample and the larger population it represents; usually calculated by estimation

adequacy

extent to which a qualitative study obtains enough data to provide a rich description of the phenomena of interest

external validity

extent to which findings of a study can be generalized to a larger population; major threats are people, places and time

probability sampling methods

include simple random sampling, stratified random sampling, systematic sampling, cluster sampling

non-probability sampling

includes convenience sampling, purposive sampling, snowball/network sampling, quota sampling

cluster sampling (probability sampling)

individuals are not randomly selected; groups or programs are selected, and every member of the group or program is invited to participate in the study

key informants

individuals who are in positions or have information that will be more beneficial compared with others in the organization

population

larger group of people that have the characteristics for participating in research study

Snowball/ network sampling (non-probability sampling)

method in which initially identified subjects provide names of others who may meet the study criteria

sampling in quantitative research

must define population from start; main purpose is to accurately draw conclusions about the population; sample size is established after the research design is determined

sampling in qualitative research

two principles of appropriateness and adequacy; randomization and number of participants are not of interest

selection of subjects

revolves around the nature of research question, the research approach, and practical considerations such as access, budget, time, space, etc.

theory-based selection

seeking individuals exemplifying a particular theoretical construct

maximum variation

seeking individuals with extremely different experiences of the phenomena; exploring the broadest range

homogenous selection

seeking informants with the same experience; exploring depth of phenomena

sample

smaller group of people from the population who participate in the study; represent the larger population

Types of individuals useful to qualitative research

social gadflied, constant observers, everyday philosophers, marginal people

general rule of thumb for most OT research is determining sample size

striving for the largest sample possibe; problems with sma;; sample size; not worth undertaking due to possible Type 2 Error; no standards or set rules for the right number of informants; the quality of data drives the sampling process-- when no new information is obtained, the right number has been achieved

exclusion criteria

the characteristics that a person cannot have in order to participate in a given research study; typically factors that could potentially confound the results of study or prevent individual from participating

inclusion criteria

the characteristics that a person must have in order to participate in a given research study

appropriateness

the extent to which a qualitative study identifies participants who can best inform the phenomena under study

statistical power

the liklihood the finding of statistical significance actually exists; min acceptable level is .80

effect size

the magnitude of statistical significance

target population

the population to which a quantitative researcher wants to generalize the study findings; determined by inclusion and exclusion criteria

social gadflied

the well-liked and lively individuals who mix with and talk to everyone in the group

subject pool

those who are eligible to participate in study; must possess inclusion criteria and not possess the exclusion criteria and are available for selection

constant observers

those who are the longer, well-established members of the group who will freely speak of the details of past events

marginal people

those who do not feel like they really belong to the group of feel ambivalent about the group. Because they do not have strong loyalty they will often talk to outsiders and be able to give valuable insights about the group