Zusammenfassung der Ressource
Variables, Scales of
Measurement, Validity
& Reliability
- Variables
- the factors that you are interested
- any quantitative measurement of an entity, attribute, or
phenomenon being studied in the study sample.
- Independent aka Study/Treatment variable
- one that is assumed to remain constant or uninfluenced
by changing conditions or circumstances in the study.
- can change the value of the
dependent variable (DV)..
- cause of the DV and should always
precede the DV and has a potential
influence on it
- FIXED
- Values= Levels
- Dependent aka Outcome variable
- changes in ways that are determined by the
influence of an independent variable or external
factors.
- value of the DV can be affected by the IV
- value of the DV depends on the action of levels of the IV
- the phenomenon that the researcher seeks to understand, explain or predict.
- Confounding
- sometimes called extraneous or intervening) variable(s)
- Aim of research
- identify how independent (or study) variables
- influence a dependent (or outcome) variable
- preferably to develop a generalisable model (through statistical analysis)
- can explain and predict that relationship
- identification of variable characteristics is
very important in planning, conducting and
critically examining research.
- Measurements
- involves the process of description and quantification in research
- relates to the recording of physical or behavioural
characteristics by assigning a value to aspects
- quality, quantity, frequency or degree of these attributes.
- use of an instrument or tool that is capable of measuring the
magnitude of the attribute (or variable) under evaluation by
using a calibrated scale
- involves assigning a value (usually numerical) to an object
- can be measured directly (length, width, death
rate) whilst others can only be indirectly measured
through an abstraction
- Categorical
- variables with discrete values rather
than incremental placement along a
continuum
- assign values to categories
- gender, diagnosis and country of birth
- measured using nominal or ordinal scales
- Continuous
- measured along an infinitely divisible scale.
- one that can take on a large range of values representing a continuum.
- height, weight, blood pressure and age
- measured using interval or ratio scales.
- Continuous tranformed into categorical but not vice versa