Elements of research design part 1:Independent variable,dependent variables

Question 1

___________________
▪ the presumed cause in an experimental study (e.g., drug vs placebo).
▪ All other variables that may impact the dependent variable are controlled, while this value is under the researcher’s control
▪ Other names are treatment variable, manipulated variable, predictor variable

Answer 1

Independent Variable

Question 2

______________
▪ the presumed effect in an experimental study.

Answer 2

Dependent Variable

Question 3

The values of the dependent variable depend upon another variable, the independent variable.

Also called the ___________variable.
▪ Examples:
* weight in an randomized controlled trial (RCT) of weight-loss drug; CV events in an RCT of an antihypertensive drug

Answer 3

outcome

Question 4

____________________
A variable that obscures the effects of another variable (dependent variable).
▪ Example is patients with fewer comorbidities receive the drug (vs a placebo)

Answer 4

Confounding

Question 5

An extraneous variable that an investigator does not wish to examine in the study, so it is controlled
▪ Also called a covariate

Answer 5

Control variable

Question 6

also called nominal variable
▪ It is usually an independent or predictor variable that contains values indicating membership in one of several possible categories like 100 mg treatment, 200 mg treatment or placebo treatment (no meaningful order)

Answer 6

Categorical variable

Question 7

_____________ Variables:
▪ special case of a categorical variable that only takes two values (Drug A vs Drug B)
▪ Can be observations that occur in one of two possible states (rated 0s and 1s) or a control variable that takes two values like males vs females
▪ Also called a dichotomous variable

Answer 7

Binary

Question 8

The variable takes on a countable number of values, often these values represent counts such as the number of ER visits in a year (integers)

Answer 8

Discrete

Question 9

A variable used to rank a sample of patients with respect to some characteristics
▪ Differences and different points of the scale are not necessarily equivalent
▪ Example:

Anxiety can be rated none, mild, moderate, and severe or 1,2,3,4.
(obvious order)

Answer 9

Ordinal

Question 10

_____________________
▪ A variable that is not restricted to particular values (other than limited by the accuracy of the measuring instrument) like weight or height
▪ Equal size intervals on different parts of the scale are assumed, if not demonstrated
▪ Also called interval variable

Answer 10

Continuous

Question 11

Types of Studies and Research Designs
Experimental: ___________________
▪ Treatments are assigned and outcomes are observed

Answer 11

RCTs(Randomized control trials)

Question 12

Non-experimental: _____________

▪ include case reports, case series, cross-sectional (surveys), case control, cohort (prospective or retrospective)

Answer 12

observational

Question 13

Clinical Trials: Advantages
o strongest evidence of __________ relationships between treatment and outcomes
o basis for clinical and public health policy
o eliminate/minimize _______ and confounding

Answer 13

cause-effect, bias,

Question 14

Clinical Trials: Disadvantages
-Require ______samples and multiple sites for validity (costly)
-results may not always apply to the _____
-ethical limitations make RCTs impossible in certain contexts:
-adverse interventions like cigarettes, interventions already widely used

Answer 14

large, real world

Question 15

Study participants
ideal accessible population:
* ________ for disease
* candidates for treatment
* representative of _______population

Answer 15

high risk, target population

Question 16

Elements of a clinical trial:
- _____________
-______________
▪ a declarative statement that predicts the expected outcome explains or predicts the relationship or differences between two or more variables in terms of expected results or outcomes of a study

▪formulated BEFORE the study is conducted because they provide the direction for the collection, analyses, and interpretation of data

Answer 16

research question, hypotheses

Question 17

_____________:
▪ can include:
general mailings, targeted mailings, mass media, screenings (worksite,community), physician referral, internet (clinical trial registries, social media)

Answer 17

Recruitment

Question 18

_______________
▪ Eliminates selection bias
▪ reduces/eliminates confounding from known and MOST IMPORTANTLY from unknown confounders

Answer 18

Randomization

Question 19

______________/open label
all parties are aware of treatment assignment

Answer 19

unblinded

Question 20

____________/single masked
* only trial participants are unaware of treatment assignment

Answer 20

single blind

Question 21

____________/double masked
* both trial participants and clinicians are unaware of treatment
assignment

Answer 21

double blind

Question 22

_________________________
trial participants, clinicians, and data analysts are unaware of treatment assignment

Answer 22

triple blind

Question 23

Data analyses:
▪________________
* present flow diagram of patient enrollment and randomization
* describes study participants
▪ Measures of adherence and outcomes variables included

Answer 23

Baseline data

Question 24

____________- refers to how well the trial was conducted

Answer 24

Internal Validity

Question 25

_____________- whether results apply to populations outside of the study

Answer 25

External validity (generalizability)

Question 26

___________- is the most important variable after randomization and is specified in the hypothesis

Answer 26

primary outcome

Question 27

__________________are relevant to the research question

Answer 27

Secondary outcomes

Question 28

identifying key variables collected/measured in RCTs/other research studies helps determine the relevance of the study to clinical question at hand
Attention to trial’s key elements (participants, hypotheses, blinding, primary and secondary outcomes) helps identify study quality and relevance to clinical practice