Week 7: Research Design & Research Subjects

General features of research designs

Investigators research paradigm, overall design format implemented consistent with the research paradigm, number of groups studied, type(s) of data collected, role of time in the study, type and degree of control imposed, if any.

What are the two main research paradigms?

Quantitative and Qualitative.

What does the quantitative research paradigm assume?

It assumes an objective truth to be revealed by independent investigators.

What type of data does quantitative research focus on?

Standardized numerical measurements.

quantitative research strives to achieve objectivity by

imposing controsl

What is the primary goal of qualitative research?

To understand knowledge and context as subjective and relative to individuals.

What type of data does qualitative research primarily use?

Descriptive data that focuses on words.

What are the three design formats in quantitative research?

Experimental, Quasi-experimental, and Nonexperimental.

What is the difference between within-subjects and between-subjects designs?

Within-subjects compares repeated measures of the same outcome, while between-subjects compares outcomes between two or more different groups.

within-subjects

Repeated measures of an outcome

Baseline measure is compared to experimental measures after intervention

Before and after intervention

between subjects

two or more different groups compared on some outcome variable

Outcomes are compared between Two or more groups

Group A vs Group B

correlation research

the study of the naturally occurring relationships among variables

What are the two types of time elements in research designs?

Duration (cross-sectional vs. longitudinal) and Direction (retrospective vs. prospective).

cross sectional time element

Single point or limited interval

longitudinal

Repeated measures over extended period

retrospective

Looking backward over a period of time

historical information, data already collected

prospective

(adj) potential, in the future

collect own data, looking forward

control is only relevant in

quantitative research

What is the purpose of control in quantitative research?

To minimize bias and ensure the validity of results.

Bias

results hat systematically deviate from the truth

What is a Randomized Clinical Trial (RCT)?

A classic experimental design where subjects are randomly assigned to two or more groups.

RCT inludes

elements to control a number of unwanted influences that may interfere w/ results

Cohort and case-control can identify questions for

Diagnostic tests and clinical measures

Prognostic factors

experimental, quasi-experimental (single subject) designs are good for

intervention questions

Systematic reviews and meta-analyses are good for

Outcomes

Self reported outcomes

Secondary analysis

Designs for questions about Diagnostic tests and clinical measures

Usually nonexperimental, cross-sectional

goal of questions about Diagnostic tests and clinical measures

Goal is to determine the usefulness of test of interest (index test) to correctly detect pathology or impairment

Methodologic studies of clinical measures

How New instruments are developed

Existing instruments that may be modified or tested

Designs for questions about prognostic factors

chorot and case-control

Cohort types

prospective and retrospective

case-control

a type of retrospective study in which researchers begin with a group of people who already had the disease; studies that compare two groups: those who have a specific condition and those who do not have the condition

What is the main focus of outcome research?

To study the impact of clinical practice on end results experienced by patients.

efficacy

intervention measured under ideal conditions

effectiveness

Intervention measured in usual clinical conditions

Real world

Quasi-experimental

Still purposeful intervention but comparison group and/or randomization to groups are missing

types of quasi-experimental

Time series

Nonequivalent control

Single-system

nonequivalent control group design

a quasi-experimental study that has at least one treatment group and one comparison group, but participants have not been randomly assigned to the two groups

single system design

a quasi-experimental research design in which one subject receives in an alternating fashion both the experimental and control condition

Designs for CPRs

Nonexperimental design

Depends on the Intended use and the Stage of development

Identify and select clinical indicators

Initial validation

Implementation

Designs for outcome research

Studies the Impact of clinical practice in real world

Focuses on "end results" experienced by patients and clients following an episode of care

Does Not study relative efficacy or effectiveness of intervention

outcome research are typically

retroscpetive and non experimental

Studies about self-report outcome measures

Person-level end points

Methodologic study design

Person-level end pointsActivity limitations, participation restrictions, ICF impairments

Secondary analyses

Reports about collection of previously completed individual studies

Narrative review

Systematic review

Narrative review

Looks at research and summarizes it

systematic reviews: study of studies

accompanied by meta anylese

Research question identifies general group of people from whom information or participation is needed

Identification of potential candidates

Selection of appropriate number

Management during study

What is purposive sampling?

A nonprobabilistic sampling method where subjects are chosen based on specific criteria.

What is the importance of inclusion and exclusion criteria in research?

They define who qualifies as a subject and help minimize confounding variables.

inclusion criteria

Describe primary traits that will qualify someone from the population of interest as a subject

Need to be broad without including too many confounding variables

Restriction impacts ability to generalize results

exclusion criteria

describes factors that would preclude someone from being a subject

What makes people ineligible as subjects

Probabilistic sample

simple random sample

systematic sampling

stratified random sampling

Simple random sample

Every subject is given a number

Chosen randomly

Everyone has an equal probability of being selected

Creates the greatest confidence in sample validity

Produces samples that accurately reflect the populations characteristics

unbiased

Systematic sampling:

Picking a spot and then choosing every nth number from first

stratified random sampling

Population divided into subgroups (strata) and random samples taken from each strata

nonprobability sampling

convince, purposive, snowball

Convenience sampling

Subjects chosen on basis of availability

Frequently are Volunteers

self selection bias

Those that volunteer may not have characteristics of target population

consecutive sampling

Recruiting people who meet inclusion and exclusion criteria as they become available

purposive sampling

selecting sample members to study because they possess attributes important to understanding the research topic

snowball sampling

Start with a few, then recruit via word of mouth

What is the purpose of systematic reviews?

To summarize and analyze existing research studies.

Random assignment methods

- Random assignment by individual

- Block assignment

- Systematic assignment

- Matched assignment

Random assignment by individual

An assignment method in which each subject is randomly allocated to a group based on which side of a coin lands upright or which number is pulled from a hat

Nonrandom assignment methods

Frequently in epidemiological studies where Naturally occurring groups

What is the significance of sample size in research?

It determines the number of subjects needed to detect statistically significant relationships.

What is the main characteristic of nonexperimental designs?

They do not impose interventions and are often observational.

What is the role of masking in research studies?

To prevent bias by keeping subjects unaware of certain aspects of the study.

What is the difference between qualitative and quantitative data?

Qualitative data is descriptive and focuses on words, while quantitative data is numerical and focuses on measurements.

What is a snowball sampling method?

A nonprobabilistic method where existing subjects recruit future subjects through word of mouth.

What does 'cross-sectional' research design refer to?

Research that collects data at a single point in time.

What does 'longitudinal' research design involve?

Repeated measures over an extended period.

What is the purpose of methodologic research?

To develop and test new or existing instruments for data collection.

What is the definition of a target population in research?

The total group of individuals to whom researchers wish to apply their findings.

ACCESIBLE POPULATION

Potential subjects who could be available for study

Sample size

Researchers required to report the number of subjects who ultimately participated in a study (sample size)

Statistical Power

the likelihood of finding a statistically significant difference when a true difference exists

type II error

failing to reject a false null hypothesis

stratified sampling

The population is split into non-overlapping groups(strata) then simple random sampling is done

Collects same info as simple random but with less people

Sample

a subset of the population

subjects

Individuals, organizations, or other units of analysis who participate in the study

What is statistical power?

The probability that a statistical test will identify a relationship or difference if it is present.

What are Type 1 and Type 2 errors?

Type 1 error is a false positive result, while Type 2 error is a false negative result.

What does 'N' represent in sampling methods?

N represents the size of the population.

What is the goal of sampling?

To create a sample that is representative of the population it is drawn from.

What is simple random sampling?

A method where every member of the population has an equal chance of being selected for the sample.

Why is simple random sampling often impractical?

Because it can be difficult to implement when populations are large.

What is stratified sampling?

A method where the population is split into non-overlapping groups (strata) and then simple random sampling is performed within those groups.

What is systematic sampling?

A method where every nth individual from the population is included in the sample.

What is convenience sampling?

A method where easily obtained individuals from the population are selected, which may lead to biased results.

What is snowball sampling?

A method where existing study subjects recruit future subjects from among their acquaintances.

What is sampling error?

The difference between the sample mean and the population mean.

What is the primary assumption of quantitative research paradigms?

There is a single objective reality that can be measured and analyzed.

What is the primary assumption of qualitative research paradigms?

There are multiple constructed realities that are context-dependent.

What is ethnography in research design?

A holistic analysis of a culture, examining how individual behaviors are shaped by cultural contexts.

ethology

Observation of behaviors in a natural context

Asks how do individuals behave in this setting

Grounded Theory

an inductive method of generating theory from data by creating categories in which to place data and then looking for relationships among categories

Historical analysis

What does phenomenology analyze?

Experiences, interpretations, and meanings to understand how individuals make sense of their interactions.

What is discourse analysis?

An analysis of the form, content, and rules of conversations to understand communication within a setting.