Concepto de Medición

Introduction to Measurement Scales

Understanding Measurement

• The discussion begins with an overview of measurement scales, emphasizing the classification of variables based on their measurement levels.

• Measurement is defined as relating a numerical or symbolic relational system to an empirical relational system through specific rules, expanding the concept beyond mere numbers.

• Measuring involves associating numbers or symbols with objects according to certain rules, highlighting the importance of consistency in data representation.

Key Concepts in Measurement

• The relationship between values must be respected; for example, consistently assigning '2' to males and '1' to females maintains equality or difference in categorization.

Levels of Measurement

Nominal Level

• Nominal measurement involves attributes where relationships are only expressed in terms of equality or difference; examples include clinical diagnoses categorized by manuals like DSM-5.

Ordinal Level

• Ordinal measurement introduces hierarchy among values, allowing them to be ordered but not quantified; an example is satisfaction scales (e.g., Likert scale), which indicate relative satisfaction without precise distances between levels.

Interval Level

• Interval measurement includes units that allow for distance calculation between values, though zero is arbitrary; psychological tests like Beck's Depression Inventory illustrate this concept where '0' does not signify absence but rather a defined state according to theory.

Ratio Level

• Ratio measurement features an absolute zero point that allows for both distance and proportion calculations; examples include reaction time measurements where '0' indicates true absence of time.

Summary of Measurement Levels

Recap of Levels

• A summary outlines the four levels: nominal (equality/difference), ordinal (order), interval (arbitrary zero), and ratio (absolute zero), emphasizing how each level builds upon the previous one regarding complexity and analytical capability.