WEEK 2: SAMPLING DATA COLLECTION

Question 1

Probability Sampling

Answer 1

Involves using selection techniques where in the probability of selecting each sampling unit is known

Question 2

Stratified Sampling

Answer 2

RANDOM
- 3 from each stratum are randomly selected
Random samples from distinct groups (i.e sex: male, female. Geography: urban, rural)

Question 3

Simple Random Sampling

Answer 3

most challenging and expensive
- each person has an equal chance of being selected

Question 4

Cluster Sampling

Answer 4

• Convenient and less expensive
• Lack random selection
• Natural clusters (schools, neighborhoods) rather than individuals units
• Observations are made on ALL units within a cluster

Question 5

Multistage Sampling

Answer 5

• Cluster is involved in this sampling
• Primary sampling units are selected
  I.e Western students
  Secondary units selected within primary units
  I.e Students in Health Sci program
  Can have more levels
  Teriery units - i.e students at western in the health sci program, in 2nd year
  Every type of person involved in this sample

Question 6

Convenience Sampling

Answer 6

selection from a non-probability based source population due to ease of access to those individuals, schools, workplaces, organizations or communities

Question 7

Purposive Sampling

Answer 7

recruitment of the participants for a qualitative study based on the special insights they can provide

Question 8

Key Informants

Answer 8

individuals selected to participate in a qualitative study because they have expertise relevant to the study question

Question 9

Berksons Bias

Answer 9

can occur when cases and controls for a study are recruited from hospitals and therefore are more likely than the general population to have comorbid conditions

Question 10

Healthy worker bias

Answer 10

can occur when participants are recruited from occupational populations and therefore are systematically heather than the general population

Question 11

Exclusion bias

Answer 11

occurs when different eligibility criteria are applied to cases and controls, such as when controls with health conditions related to an exposure are excluded but cases with those comorbidities are not excluded

Question 12

Type 1 Error (A)

Answer 12

occurs when a study population yields a statistically significant test result even thought a significant different or association does not actually exist in the source population
- Rejected null hypothesis even tho it was true

Question 13

Type 2 Error (B)

Answer 13

occurs when a statistical test of data from research finds no significant result even thought a significant difference or association actually exists in the source population
- Null hypothesis is false and failed to reject it

Question 14

Interview

Answer 14

is: the process of verbally asking a participant questions and recording that persons responses

Question 15

Self Administered Survey

Answer 15

questionnaire form that participants complete by themselves, using either a paper and pencil version or online

Question 16

Semi Structured Interview

Answer 16

the interview starts with a list of open ended questions that will be asked of each participant, but these questions or lists of topics are merely starting points for electing responses from participants

Question 17

Probing

Answer 17

is an interview technique that prompts an interviewee to provide a more complete or specific response

Question 18

Interviewer Bias

Answer 18

occurs when interviewers systematically questions cases and controls or exposed and unexposed members of a study population differently, such as probing only individuals they believe to have the disease or exposure of interest for more information

Question 19

Uniformity

Answer 19

easiest to accomplish when all interviewers are provided with the tools they need to follow a standardized set of procedures

Question 20

Close ended questions

Answer 20

allow a limited number of possible responses
-date and time questions
-numeric questions
-categorical
o ranked (ordinal) categorical answers have an inherent order
o unordered (nominal) categorical answers do not have any built in order
- paired comparisons

Question 21

Pros and Cons of a self administered survey

Answer 21

pros: cost and time efficient, possibility of approaching a large number of partipants, honest answer to sensitive questions
cons: low literacy populations, limited internet

Question 22

1. Order of Questions

Answer 22

• better to start with easy or at least general questions before moving to more difficult or sensitive questions
• it is often best to group similar questions with similar response types, so that they are asked consecutively

Question 23

Pilot Testing

Answer 23

A small scale preliminary study conducted to evaluate the feasibility of a full scale research project

Question 24

Target Population

Answer 24

broad population to which the results of a study should be applicable

Question 25

Source Population

Answer 25

sometimes called a sample frame, a week defined subset of individuals from the target population from which potential study participants will be studied

Question 26

Sample Population

Answer 26

individuals from a source population who are invited to participate

Question 27

Study Population

Answer 27

eligible participants who consent and complete required study activities

Question 28

Sampling Bias

Answer 28

occurs when the individuals sampled for a study systematically are not representative of the source population as a whole

Question 29

Census

Answer 29

is a complete enumeration of a population, such as a count of every resident of a country or inpatients at a particular time and area of a hospital

Question 30

Nested case control study

Answer 30

uses the participants of a large longitudinal cohort study as the source population for both cases and controls

Question 31

Eligibility Criteria

Answer 31

study comprise the inclusion criteria that must be present for an individual to be allowed. To participate in a study and the exclusion criteria that require an individual to be removed from study population

Question 32

Vulnerable Populations

Answer 32

whose members might have limited ability to make an autonomous decision about volunteering to participate in a research study

Question 33

Key Informants

Answer 33

: individuals selected to participate in a qualitative study because they have expertise relevant to the study question

Question 34

Sample Size

Answer 34

number of observations in a data set, usually the number of individual humans in the study population - Large samples from a population are usually better than small ones at yielding a sample mean close to the true population value

Question 35

Confidence Interval

Answer 35

statistical estimate of the range of likely values of a parameter in a source population based on the value of that statistic in a study population

Question 36

Sample size calculator

Answer 36

is a tool used to identify an appropriate number of participants to recruit for a quantitative study

Question 37

What type of error occurs when a statistical test of data from the study population finds no significant result even though a significant difference or association actually exists in the population

Answer 37

Type 2 Error

Question 38

Agent

Answer 38

pathogen or chemical or physical cause of disease/injury

Question 39

Likert scale

Answer 39

- present ordered responses to a questionnaire item that asks participants to rank preferences numerically such as using a scale where 1 means you strongly disagree

Question 40

Anonymity

Answer 40

- the inability of a participant's identity to be discerned from his/her responses to a survey instrument or records in a database

Question 41

Habituation

Answer 41

error that occurs when participants completing a questionnaire/interview become accustomed to giving a certain response (agree) That they continue to reply with the same response even when it does not match their perspective

Question 42

Skip-logic

Answer 42

codes that can automatically hide irrelevant questions from participants based on their responses to filter questions

Question 43

Cronbach’s Alpha

Answer 43

measure of internal consistency used with variable that have ordered responses Expressed with a 0 or 1

Question 44

Test-Retest Reliability

Answer 44

demonstrated when people who take a baseline assessment and then retake the test later have the same scores each time the are tested

Question 45

Content validity/ Logical Validity

Answer 45

- present when subject matter experts agree that a set of survey items captures the most relevant information about the study domain

Question 46

Face Validity

Answer 46

present when content experts and users agree that a survey instrument will be easy for study participants to understand and correctly complete

Question 47

Construct Validity

Answer 47

present when a set of questions in a survey measles the theoretical construct the toolo is intended to assess

Question 48

Convergent Validity

Answer 48

present when 2 items that the underlying theory says should be related are shown to be correlated

Question 49

Back translation/ double translation

Answer 49

one person translates the questionnaire from the original language to a new language and then a second person translates the survey instrument in the ne language back into the original language