Concepts Journal Club 3

Question 1

Cross-over

Answer 1

First one group receives A, later followed by B, while the other group first receives B, later followed by A. Benefit is that they can become their own control group, however the first treatment can effect the second treatment (carry-over effect).

Question 2

Counterbalancing

Answer 2

Neutralize or cancel by exerting an opposite influence.

Question 3

Enforcing allocation concealment

Answer 3

A technique used to prevent selection bias in RCT’s by concealing the allocation sequence from those assigning participants to the intervention groups, until the moment of assignment. Thus it prevents researchers from influencing which participants are assigned to the intervention or control group.

Question 4

Placebo

Answer 4

A substance that has no therapeutic effect, used as a control in testing new drugs. Sometimes no placebo when there should be one, because it is not ethical to give people not a medicine while they actually need it to get better.

Question 5

Outcome measure(s)

Answer 5

Determination and evaluation of the results of an activity, plan, process, or program and their comparison with the intended or projected results. You have the primary outcome (where you are looking for) and secondary outcome (align with any secondary study aim or objective).

Question 6

Blinding / Masking

Answer 6

When information about the test is masked (kept) from the participant/researchers, to reduce or eliminate bias. Double blind when both the researchers and participants do not know.

Question 7

Generalisability

Answer 7

The extent to which the findings of a study can be applied to other situations. It can be divided into population generalisability, environmental generalisability and temporal generalisability.

Question 8

Error (random, systematic), Noise (origins of error, researcher)

Answer 8

Systematic error is a consistent, repeatable error associated with faulty equipment, or a flawed experiment design, and it will cause bias. Random error has no pattern, they are unpredictable and unavoidable. Noisy data is data that is corrupted, or distorted, or has a low Signal-to-Noise Ratio.

Question 9

Confounding

Answer 9

The effects of the exposure under study on a given outcome are mixed in with the effects of an additional factor (or set of factors) resulting in a distortion of the true relationship.

Question 10

External validity

Answer 10

The extent to which the results of a study can be generalized to other situations and to other people.

Question 11

Internal validity

Answer 11

The extent to which a causal conclusion based on a study is justified, which is determined by the degree to which a study minimizes systematic error.

Question 12

Test validity

Answer 12

The extent to which a test measures what it is supposed to measure.

Question 13

Experimental validity

Answer 13

Refers to the manner in which variables influence both the results of the research and the generalizability to the population at large.

Question 14

Face validity

Answer 14

The extent to which a test is subjectively viewed as covering the concept it claims to measure.

Question 15

Content validity

Answer 15

Refers to the extent to which a measure represents all facets of a given construct.

Question 16

Criterion validity

Answer 16

The extent to which a measure is related to an outcome. So do the results accurately measure the concrete outcome they are designed to measure?

Question 17

Instrument reliability

Answer 17

Way of ensuring that any instrument used for measuring experimental variables gives the same results every time.

Question 18

Inter-rater reliability

Answer 18

Degree of agreement among raters. It gives a score of how much homogeneity there is in the ratings given by judges, and it is one of the aspects of test validity.

Question 19

Intra-rater reliability

Answer 19

Degree of agreement among repeated administrations of a diagnostic test performed by a single rater.

Question 20

(Pre-)stratification

Answer 20

The partitioning of subjects and results by a factor other than the treatment given (e.g. by gender). Stratification can be used to control for confounding variables.

Question 21

Effect modifier (homogeneity in prognostic factors)

Answer 21

A factor that modifies the effect of a putative causal factor under study, e.g. age is an effect modifier for many conditions.

Question 22

Continuous variable

Answer 22

A variable that has an infinite number of possible values.

Question 23

Discrete variable

Answer 23

A variable that can only take on a certain number of values (it represents counts).

Question 24

Interval variable

Answer 24

The intervals between the values of the interval variable are equally spaced.

Question 25

Ratio variable

Answer 25

Has all the properties of an interval variable, and also has a clear definition of 0.0. When the variable equals 0.0, there is none of that variable.

Question 26

Categorical variable

Answer 26

A variable that has two or more categories, but there is no intrinsic ordering to the categories.

Question 27

Control variable

Answer 27

Anything that is held constant or limited in a research study. It is a variable that is controlled because it could influence the outcomes.

Question 28

Moderating variable

Answer 28

Moderators can be categorical variables or quantitative variables. They influence the relationship between a dependent and an independent variable.

Question 29

Intermediate variable

Answer 29

Variable that occurs in a causal pathway from a causal (independent) variable to an outcome (dependent) variable. It causes variation in the outcome variable and itself is caused to vary by the original causal variable.