Explain the four levels of measurement: nominal, ordinal, interval, and ratio.

Here is a concise note on the levels of measurement:

• Nominal: Unordered categories (e.g., gender).
• Ordinal: Ordered categories, unequal intervals (e.g., satisfaction levels).
• Interval: Ordered, equal intervals, no true zero (e.g., temperature in °C).
• Ratio: Ordered, equal intervals, true zero, meaningful ratios (e.g., height).