Part 4: Experiments

Question 1

Observation:

Answer 1

Registering an empirical phenomenon.

Question 2

Manipulation:

Answer 2

Changing a factor in a study.

Question 3

Intervention:

Answer 3

Changing an independent variable.

Question 4

Control:

Answer 4

Reducing the influence of disturbing factors from influencing the outcome.

Question 5

Independent variables:

Answer 5

Variables that are hypothesised to affect the dependent variable.

Question 6

Dependent variables:

Answer 6

The variable that changes depending on the changes to the independent variable.

Question 7

Experiment:

Answer 7

An observational process characterized by control of the background factors (often through manipulation), intervention on the real target variable through manipulation and observation of the difference caused by this intervention.

Question 8

Method of difference:

Answer 8

By creating two identical groups, and making an intervention on only one of them, the causal effect of that intervention can be studied, since the intervention is the only factor different between the groups.

Question 9

Control group:

Answer 9

A contrast class that is not subjected to the intervention, but is similar to the treatment group in all other relevant aspects.

Question 10

Treatment group:

Answer 10

A class that is subjected to the intervention.

Question 11

Observational study:

Answer 11

An observational process characterized by control of the background factors and observation of an outcome, lacking an intervention.

Question 12

Natural experiment:

Answer 12

An observational study where circumstances are organized as if there had been manipulation for intervention and control but no manipulation is in fact done.

Question 13

Field experiment:

Answer 13

An experiment where there is manipulation for intervention, but where several background variables are not controlled, in particular not controlled through manipulation.

Question 14

Laboratory experiment:

Answer 14

An experiment where there is manipulation for intervention and where all or most relevant variables are controlled.

Question 15

Simulation experiment:

Answer 15

A model study where the model is created as to mimic an experiment, but where the variable that is intervened on is only represented, rather than actually present.

Question 16

Internal validity:

Answer 16

An inference about an experimental system is internally valid, if the relation between intervention and observed effect inferred from the experiments is indeed true and is not confounded by uncontrolled background factors.

Question 17

Observer effect / influence problem:

Answer 17

The act of observation changes what is observed.

Question 18

Confirmation bias / interpretation problem:

Answer 18

The observation is registered incorrectly due to psychological properties of the observer.

Question 19

Placebo effect:

Answer 19

The therapeutic effect that an inert substance or treatment, designed to have no therapeutic value, has on a patient

Question 20

Selection bias:

Answer 20

A factor influences the selection of the sample, or the division in to test and control group, which one did not aim to create.

Question 21

Repetition:

Answer 21

Performing a study again, exactly following the description of the original study.

Question 22

Reproduction:

Answer 22

Repeating a study and obtaining the same result as in the original study.

Question 23

Replication:

Answer 23

Performing a variation of a study with the intention to achieve the same result, where some aspect of the study has been changed to learn how this aspect influenced the result.

Question 24

Constancy:

Answer 24

Holding background factors constant between test and control group or between trials in a study.

Question 25

Elimination:

Answer 25

Removing the influence of a background factor

Question 26

Blinding:

Answer 26

Eliminating observer effect or the influence problem through limiting information about the study to participants or observers.

Question 27

Single blinding / subject blinding:

Answer 27

Blinding the participants in a study, for instance about whether they are in the test or control group.

Question 28

Experimenter blinding:

Answer 28

Blinding the observers in a study, for instance about which subjects are in the test and control group.

Question 29

Double blinding:

Answer 29

A study is double blind if both subject blinding and experimenter blinding are implemented

Question 30

Separation:

Answer 30

Registering the effect of a background variable.

Question 31

Randomization:

Answer 31

Using a random process to divide into test and control, for instance by flipping a coin.

Question 32

Random sampling:

Answer 32

Using a random process to collect a sample from the population. Not to be confused with randomization.

Question 33

Evidential hierarchies:

Answer 33

A ranking of types of evidence based on the processes that produced this evidence.

Question 34

Data stratification:

Answer 34

Dividing a sample into categories based on specific properties before randomizing, thus ensuring that these properties are correctly represented in the test and control groups, for instance mirroring their distribution in the population.

Question 35

Known factor:

Answer 35

A factor which you are aware of constitutes a relevant background factor.

Question 36

Unknown factor:

Answer 36

A factor which is a relevant background factor, but which you are unaware of.

Question 37

External validity:

Answer 37

An inference from an experimental system to a different target of interest is externally valid, if the conclusion holds not only for the system but also for the target, for instance an inference from a sample to a population.