# Variables, Scales of Measurement, Validity & Reliability

Mind Map by , created about 6 years ago

## HBS108 (Week 6 & 7) Mind Map on Variables, Scales of Measurement, Validity & Reliability, created by shirley.ha on 09/02/2013.

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 Created by shirley.ha about 6 years ago
RCT
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Variables, Scales of Measurement, Validity & Reliability
1 Variables
1.1 the factors that you are interested
1.1.1 any quantitative measurement of an entity, attribute, or phenomenon being studied in the study sample.
1.2 Independent aka Study/Treatment variable
1.2.1 one that is assumed to remain constant or uninfluenced by changing conditions or circumstances in the study.
1.2.2 can change the value of the dependent variable (DV)..
1.2.3 cause of the DV and should always precede the DV and has a potential influence on it
1.2.4 FIXED
1.2.5 Values= Levels
1.3 Dependent aka Outcome variable
1.3.1 changes in ways that are determined by the influence of an independent variable or external factors.
1.3.1.1 value of the DV can be affected by the IV
1.3.1.1.1 value of the DV depends on the action of levels of the IV
1.3.2 the phenomenon that the researcher seeks to understand, explain or predict.
1.4 Confounding
1.4.1 sometimes called extraneous or intervening) variable(s)
2 Aim of research
2.1 identify how independent (or study) variables
2.1.1 influence a dependent (or outcome) variable
2.1.1.1 preferably to develop a generalisable model (through statistical analysis)
2.1.1.1.1 can explain and predict that relationship
2.1.1.1.1.1 identification of variable characteristics is very important in planning, conducting and critically examining research.
3 Measurements
3.1 involves the process of description and quantification in research
3.1.1 relates to the recording of physical or behavioural characteristics by assigning a value to aspects
3.1.2 quality, quantity, frequency or degree of these attributes.
3.2 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
3.3 involves assigning a value (usually numerical) to an object
3.3.1 can be measured directly (length, width, death rate) whilst others can only be indirectly measured through an abstraction
3.3.1.1 Categorical
3.3.1.1.1 variables with discrete values rather than incremental placement along a continuum
3.3.1.1.2 assign values to categories
3.3.1.1.2.1 gender, diagnosis and country of birth
3.3.1.1.3 measured using nominal or ordinal scales
3.3.1.2 Continuous
3.3.1.2.1 measured along an infinitely divisible scale.
3.3.1.2.1.1 one that can take on a large range of values representing a continuum.
3.3.1.2.2 height, weight, blood pressure and age
3.3.1.2.3 measured using interval or ratio scales.
3.3.1.2.4 Continuous tranformed into categorical but not vice versa