Chapter 8 Flashcards
Defined as the process of assigning numerals to variables to represent quantities of characteristics according to certain rules
Measurement
What are the uses of measurement
Describing quantity to determine value
Making decisions
Drawing comparisons
documenting change or progress
Discriminating
Predicting outcomes
Dichotomous variables can only take on how many variables
2
Ex of dichotomous variables
Yes or no on a survey
Polytomous variables can have how many values?
Many
Ex of polytomous variables
5 point opinion scale
can have any value along a continuum within a defined range
Continuous variables
Ex of continuous variable
Wt in lbs
Discrete variables can only be described in
Whole integer units
Ex of discrete variables
Heart rate in beats per minute
Ex of direct observations of a physical property
range of motion in degrees or length in centimeters
For measures that are not observable, use an indirect or proxy measure. An example of this is
the height of a column of mercury to measure temperature
Measured as some value assumed to represent the underlying variable
Abstract variables
Ex of abstract variables
Intelligence, health, strength
Levels of measurement
●Nominal
●Ordinal
●Interval
●Ratio
Classifications
●No relative order
●Numbers, letters or words may be used as category labels
•Blood type
•Gender
•Diagnosis
●Arithmetic properties: counting (frequency)
Nominal scale
Numbers indicate rank order
●Intervals inconsistent or not known
●Examples: manual muscle test, function, pain
●Arithmetic properties: counts, percentages
•Medians useful for central tendency
•Cannot be added, subtracted, multiplied, or divided
Ordinal scale
Numbers indicate rank order and demonstrate equal intervals
●No true zero
●Examples: temperature in Fahrenheit or Celsius
●Arithmetic properties: addition and subtraction
Interval scale
Numbers indicate equal intervals and have a true zero
●Examples: age, height, weight
●Arithmetic properties: addition, subtraction, multiplication, and division
Ratio scale
What is the relevance of measurement scales?
Determination of which mathematical operations are appropriate
●Determination of which interpretations are meaningful
●Statistical procedures
•Parametric versus nonparametric tests
