Selection and assignments of participants

Question 1

selection/sampling

Answer 1

• process by which subgroup of participants is selected from a larger group of potential participants
• affects generalizability of study results

Question 2

Assignment

Answer 2

• process by which participants in sample are assigned to groups within a study
• want similar patients in each groups

Question 3

Population
sample

Answer 3

1. total group of interest
2. subgroup of group of interest

Question 4

target population

Answer 4

group to whom researchers hope to generalize findings

Question 5

accessible population

Answer 5

• group of potential participants who are available for a study (not always represent target population

Question 6

probability

Answer 6

randomization at some point in the process

Question 7

non probability

Answer 7

no randomization at any point in the process

Question 8

Simple random sampling

Answer 8

• each member of population has equal chance of being selected for sample
• selection of each subject is independent of selection of other participants
• can mean the same person can be selected again with equal chance

Question 9

Systematic sampling

Answer 9

• researchers selects every nth person on the list
• for sample of 300 from a population of 3000 you would take every 10 patients

Question 10

stratified sampleing

Answer 10

• used when certain groups must be represented in adequate #s within a sample
• TKA study: patients from each hospital (8 different hospitals)
• can be proportional (% of the population) or nonproportional (each hospital would get the same number/%)

Question 11

cluster sampling

Answer 11

• used of natural occurring groups as sampling units
• picking a state, city, hospital

Question 12

Convenience sampling

Answer 12

• use of readily available participants
• commonly used in rehabilitation research
• group of people that are easily available to you

Question 13

snowball sampling

Answer 13

• used when potential members of sample difficult to identify
• researchers identify a few participants who are then asked to identify other potential members of the sample
• used when there is criteria that may be embarrassing for people to admit

Question 14

purposive sampling

Answer 14

• usually used for qualitative research
• used when researchers has specific reason for selecting particular participants for a study
• usually only used when the researchers have a particular group of people
• goes out and hand picks participants that they believe will illustrate their variables

Question 15

Purpose vs convenience sampling

Answer 15

• purposive: qualitative research with a goal of diversity
• convenience: quantitative research with a goal of representative sample

Question 16

Random assignment by individual

Answer 16

• groups can come out unequal that is not always what you want for studies
• each individual gets assigned a random group
• each individual has the same probability of getting assigned any group

Question 17

random assignment by block

Answer 17

• groups get assigned individuals and groups are made evenly

Question 18

systematic assignment

Answer 18

• individuals are assigned to groups in order so group 1 can have every 5th person

Question 19

matched assignments

Answer 19

• participants are mated by important characteristics
• subgroups to match participants
• ex: gender or age matched between groups

Question 20

consecutive assignment

Answer 20

• previous types of assignment only useful when existing sample is available for assignment to groups
• used with consecutive sampling, such as subjects who enter studies as they undergo surgery or enter health care facility
• develop ordered list with group assignments in advance
• as participants enter study, given consecutive #s and assigned to group indicated for each #