Quantification & Measurement + displaying Describing Data

What is quantification in psychology?

he process of assigning numbers to psychological phenomena or objects.

Why is measurement in psychology often indirect?

Many psychological phenomena are not inherently quantitative and must be represented with numbers.

What is S.S. Stevens' definition of measurement?

“The assignment of numerals to objects or events according to rules.”

What are the four scales of measurement in Stevens' framework?

Nominal, Ordinal, Interval, Ratio.

What is an example of a ratio scale?

Number of speeding tickets.

Why are OC/PC variables used in psychology?

They are ordinal but treated as continuous due to having 5+ ordered categories.

What are dichotomous and nominal variables?

Dichotomous = 2 unordered categories; Nominal = 3+ unordered categories.

What are OC/PC variables?

Ordered-categorical/pseudo-continuous variables: ordinal scales used as if continuous.

What was Joel Michell’s main critique of psychological measurement?

It is “pathological” because it assumes psychological attributes are quantitative without testing this hypothesis.

What is the issue with reductionism in measurement?

It oversimplifies complex psychological phenomena by ignoring their context.

What was Gunter Trendler’s critique?

Psychology lacks precise, direct measurement instruments like those in physical sciences.

What is a frequency distribution?

A table showing how often each value of a variable occurs in a dataset.

What are relative and percentage frequencies?

Relative = f/N; Percentage = (f/N) × 100.

What are cumulative frequencies?

The running total of frequencies up to a value (can be raw, relative, or percentage).

What are bins in grouped frequency tables?

Ranges of values grouped together in the table rows.

What are real limits?

5 below and above the apparent limits, used for continuous/OC/PC variables.

When are bar graphs used?

For discrete variables (nominal or dichotomous); bars do not touch.

When are histograms used?

For continuous or OC/PC variables; bars do touch.

Why is bin width important in histograms?

It affects how clearly the shape of the distribution is shown.

What are best practices for graphs?

Use clear labels, intersect axes at 0, use appropriate scales, and avoid 3D or pie charts.