Variable types - descriptive statistics - normal distribution
PART 1
Variables
Need to know how many and what types there are. → properly organize the data set and choose the correct
statistical procedure.
How to organize:
Choosing the appropriate test:
When tidying the data set; always plot the data first to check for outliers. Plot the observation number against
the observation that is made, e.g. body height. Can be done in excel or JASP with a scatter plot.
Not all data (variables) are equal/ equivalent. This determines how you should organize the data set and
what statistical test you should choose.
1. Independent vs dependent
Independent variable (IV)
- Predictor of the outcome of the experiment or observation
- This variable is chosen and controlled by the investigator.
- Plotted on the x-axis. (abscissa)
Dependent variable (DV)
- Result or measurement
- Responds to experimental manipulation; the independent variable.
- Measured by the investigator
- Plotted on y-axis (ordinate)
2. Qualitative vs quantitative
Types of variable and levels of measurement
Qualitative variable
PART 1
Variables
Need to know how many and what types there are. → properly organize the data set and choose the correct
statistical procedure.
How to organize:
Choosing the appropriate test:
When tidying the data set; always plot the data first to check for outliers. Plot the observation number against
the observation that is made, e.g. body height. Can be done in excel or JASP with a scatter plot.
Not all data (variables) are equal/ equivalent. This determines how you should organize the data set and
what statistical test you should choose.
1. Independent vs dependent
Independent variable (IV)
- Predictor of the outcome of the experiment or observation
- This variable is chosen and controlled by the investigator.
- Plotted on the x-axis. (abscissa)
Dependent variable (DV)
- Result or measurement
- Responds to experimental manipulation; the independent variable.
- Measured by the investigator
- Plotted on y-axis (ordinate)
2. Qualitative vs quantitative
Types of variable and levels of measurement
Qualitative variable
