Exam 1 - Study Material (Sampling + Data Collection) Flashcards
What 2 types of data collection are there?
Systematic and objective
What is data collection?
It is the translation of conceptual definition into an operation or operational definition
What is measurement error?
It is the difference in the variables between what really exists and what the study measures
What are 3 different types of measurement error?
- Random- methods not standardized
- Systematic – instrument incorrect
- Protection – Fidelity or consistency of methods
What are the different types of data collection methods?
- }EXISTING DATA
- }PHYSIOLOGICAL DATA
- }OBSERVATIONAL
- }INTERVIEWS
- }QUESTIONNAIRES
◦No matter which method is chosen it should be carried out systematically and objectively
Describe existing records or available data, give an example, and what are the advantages and disadvantages of this data collection method
- Data already collected for another purpose
- Example- Chart, historical documents,
- Advantage- Time saving, helps to establish trends, avoid issues of selection bias or reactivity
- Disadvantage- Not always accessible, entry not always systematic, authenticity, underreporting, bias in data entry
Describe physiological data, give an example, and what are the advantages and disadvantages of this data collection method
- Active collection of physical or biological information, requires special equipment. Used to test intervention effect, improve performance
- Example- Hemoglobin, BP
- Advantage- Sensitive, accurate, generally unbiased
- Disadvantage- Can be changed at times, only as good as equipment, cost, training, device can be intrusive
What is observational data and what are some characteristics of it?
- A scientific selection of behaviors or phenomenon related to scientific concepts
- consistent with study’s aims
- standardized observational guide (provocation)
- there is a plan for checking and controlling observations, and recording observations
What are the different types of observations?
- No concealment without intervention
- No concealment with intervention (they are watching you and doing an intervention)
- Concealment without intervention (Think facebook, ebay)
- Concealment with intervention (
- Concealment = know or not
- Intervention = provoke or not
- Advantages- some behaviors can only observe
- Disadvantages- can be biased
What are the advantages to observation?
- Best means to get data from some populations
- ome information can only be observed
- Good for complementary information
What are the disadvantages to observation?
- Ethics- debriefing
- Response of subjects
- Bias of observer- emotions, prejudice, values
What are interviews, give an example, and what are some advantages and disadvantages?
- Direct questioning- depth, content, wording Structured/unstructured (open-ended\closed ended)
- Need an interview guide
- Require a qualitative analysis i.e. content analysis
-
Advantage:
- Rich, full information
-
Disadvantage:
- Reactivity of subject or interviewer, costly, order-order can change response
What are questionnaries?
- Instruments, scales, tools.
- Overt or covert.
- Techniques -Paper Pencil, Projective, Response: Fixed, Yes\No, Likert, Visual Analogue Scales(1-10,1-100, Faces,Examples p.280-281)
- Internet questionnaires
- Example- Brief Fatigue Inventory
What are some advantages to questionnaires?
- Most useful for variables that can not be observed or directly measured
- Less expensive
- Training easier
- Confidentiality
- Online economical
What are some disadvantages to questionnaires?
- Social desirability
- Respondent burden
- Skip around
- Internet- who is subject? Informed consent, data safety
What are the steps to instrument development?
}METHODOLOGICAL OR PSYCHOMETRIC DESIGN:
◦DEFINE CONCEPT
◦CLARIFY POPULATION
◦FORMULATE ITEMS & RESPONSE SET
◦FORMULATE INSTRUCTIONS
◦PILOT TEST
◦ASSESS FOR RELIABILITY & VALIDITY
How would you critique an instrument?
- All identified and described with rationale
- Consistent with problem & appropriate for setting and sample
- Data collection similar and consistent
- Assess fidelity
- See each specific method criteria p.286
What is sampling?
SELECTING REPRESENTATIVE UNITS OF A POPULATION IN ORDER TO REPRESENT A POPULATION
What must sampling consist of?
- WHO,WHEN,WHERE AND HOW MANY
- PLAN
- Can never test whole population so must test a sample or part of whole
- Must have a well defined set of properties
Describe some characteristics of sampling
- Sampling is a process of selecting a portion or subset of the designated population to represent the entire population.
- A sample is a set of elements that make up the population.
- An element is the most basic unit about which information is collected.
What is representative sample?
A representative sample is one whose key characteristics closely approximate those of the population.
What is the goal of sampling?
- INCREASE GENERALIZABILITY
- Decrease bias
- Increase representativeness
- Increase homogeneity
- Balance cost versus accuracy
What is a population?
A well defined set that has certain specified properties
What is an element?
The most basic unit about which information is collected
What is a target?
Entire Population of interest
What is an accessible population?
A population that meets the population criteria and is avaliable
What is inclusion criteria?
Eligibility criteria, attributes of subjects that will represent the variables of interest
What is exclusion criteria?
- Delimitations, subjects who do not possess the criteria to participate
- When reviewing a study think closely about inclusion criteria
What is probabiltiy sampling?
Sample chosen using random methods, likely to be more representative and more rigorous.
What is nonprobabiltiy sampling?
elements chosen by non-random methods
What are the different nonprobability sampling types?
- CONVENIENCE
- QUOTA
- PURPOSIVE
What is convenience sampling, give an example, what are the disadvantages and advantages?
- Most readily accessible
- Advantage- Easy
- Disadvantage-greater chance of selection bias, decrease generalizability
- Example- All families who are scheduled for a transplant evaluation
What is quota sampling, what are some advantages & disadvantages, and give an example
- Select sample on a known proportion. Build in representativeness, try to represent proportions or strata of population. Criteria based on a theory. Imp-selection criteria
- Advantage- Fairly easy, Builds in some representativeness
- Disadvantage- Selection bias
- Example- Know 60% of children TX’d male & 40% female. Sample that proportions
What is purposive sampling, what are the advatnages and disadvantages, and give an example
- Select those believed to be representative or typical of population. Assume errors in judgement will balance out.
- Advantage- Easy, allows to handpick typical
- Disadvantage- Bias increase, limited generalizability
- Example- BMT pts, experience of NP s with homeless (Qualitative- Appendix C)
What are some probability sampling types?
- SIMPLE RANDOM Sample
- STRATIFIED RANDOM Sample
- MULTISTAGE (CLUSTER Sample)
What is random assignment?
Assign randomly to group –Appendix A and p.351**
What is random selection?
Equal and independent chance of being in either group
What is a simple random sample, what are the advantages and disadvatnages, and give an example
- It is a carefully defined process where the researcher defines the population (a set), lists all the units of the population (a sampling frame), and selects a sample of units (a subset), from which the sample will be chosen via a random process (computer randomization).
Advantages:
- Decrease selection bias
- Representivness of the population is maximized
- Probability of not choosing a sample representative of the population decreases as the size of the sample increases
Disadvantages-
- Time, don’t always know all elements thus start with a convenience sample and randomize
- EX- Family perspectives of last months in life hosp./ICU. Loss of subjects due to address
What is a stratified random sample?
Population divided into homogenous strata, appropriate number from each strata chosen randomly, like quota (ex. random).
- stratify on important variable
- equal number per group or proportional
- is there enough to have subsets
What are some advantages and disadvantages for stratified random samples and give an example
- Advantages- Increase representativeness, helps to make group comparisons
- Disadvantages- Choosing critical variable information, time-consuming, costly
- Example- Test intervention on stress, coping in children with HIV/AIDS and care givers (caregivers were stratified by type)
What is multistage (cluster) sampling, what are the advantages and disadvantages, and give an example
- Successive random sampling of clusters from large to small, each step is random
- Advantage- Allows a way to narrow a large group to a specific small group
- Disadvantage- Costly, access, large numbers
- Example- AACN Thunder study
- Example p. 242 – Four stage:181 hospitals in China from 9 provinces, hospital type and nurse type
What is the criteria for a sample size?
- NO SINGLE RULE
- Design type and data analysis technique
- Sampling procedure, measurement sensitivity
- Problem or study purpose, number of variables
- Formula used or effect size
- Precision required
- Homogeneity or heterogeneity of variable/attribute
- Rate of occurrence
- Cost
What are some sample size issues?
- Sample size is determined before the study
- Plan and procedures for obtaining sample are developed before the study begins
How would you critique a sample?
- Characteristics described and are they representative of the population
- Eligibility criteria identified
- How was the sample selected and bias avoided- CRITICAL
- Is the sample size appropriate and substantiated
- What are the limitations and generalizability
What is a sampling frame?
A list of all units of a population
