What is quantitate research?
- Quantifying relationships between variables
- Measure variables on a sample of participants
- Express the relationship between variables
What are variables?
- A concept or construct
- Can have more than one value
- Can be different for each research participant
What is a constant?
- A concept or construct
- Always has the same value for each participant
Independant Vs. Dependant Variables
IV:
Explains or causes a change in another variable
Not dependant on another variable
Manipulated by the researcher
DV:
Explained or caused by IV
Level is dependant on other variable
Of interest in explaining and understanding
What does it mean to conceptualise?
To accept a nominal definition
What does it mean to operationalise?
To accept a way of measuring
What are the levels of measurement
Categorical –>
- -> Nominal –> Classifies
- -> Ordinal —> Classifies orders
Numerical –>
- -> Interval –> Classifies orders, equal intervals
- -> Ratio –> Classifies orders, equal intervals, absolute zero
Categorical Variables: Nominal Level
- Names the levels uniquely
- Variables are:
Discrete –> Data falls into categories
Non-meteric –> No order in categories
E.g. Gender, Eye colour
Categorical Variables: Ordinal Level
- Names and orders the levels
- Variables are:
Discrete –> Data falls into categories
Order in the categories, ranking - Tells whether participants are different plus that one is more or less than the other
E.g. How do you feel today
- Very unhappy
- Unhappy
- OK
- Happy
- Very Happy
Numeric Variables: Interval Level
- Categories of the variable are legitimate numbers
- Categories have equal intervals between them
- No true zero point
E.g. Relative Sitting Height (%), BMI (Kg/m2)
Numeric Variables: Ratio Level
- Most precise form of measurement
- Equal intervals between categories
- True zero point
- Tell us:
–> whether two people are different
–> whether one is more something than the other
–> How much they differ
–> What is the ratio between one from the other
E.g. age, height, weight
What are the 3 measurement concerns?
- Constraints
- Reliability
- Validity
Validity: How do we know we are measuring the concept?
- Face
- Content
- Criterion (predictive, concurrent and known groups validity)
- Construct (convergent and divergent validity)
Reliability:
- Degree of consistency in measurement
- Degree of repeatability of measurement
- Degree of agreement between different observers, raters or judges
