Research Methods 1 Levels of Measurement

Self Assessment On completion of this session you should comprehend: §The differences between subjective measures and objective measures §The nature of interval, ratio, nominal and ordinal measures

From research question to data collection §Research hypothesis - operationalisation §What are you measuring and how are you going to measure it? §Independent and dependent variables

Variables? §Parameters/Properties that vary §Independent variable - what is the experimenter going to manipulate? §Dependent variable - what is the outcome that is to be measured?

Independent and Dependent Variables § The investigation of the effect of ultrasound therapy on pain intensity levels. § The investigation of the effect of aerobic exercise on perceived mood state.

Definition of measurement “All any measurement is is a parameter chosen to represent the concept.” Dane (1990)

Types of measurements §Objective - measurement of physical quantities and qualities using measurement equipment e.g. tape measure, electric weighing scales, goniometry §Subjective - ratings or judgements by humans of quantities and qualities e.g. rating ROM by eyeball estimation §Uses?

Types of measurements §Qualitative; A ‘quality’ of the subject e.g. gender, exam grade achieved etc. A characteristic or type not a measured amount. §Quantitative; A ‘quantity’ measured with numbers each number representing a measurement.

Types and Levels of measurements §Qualitative  Nominal  Ordinal  Quantitative §Discrete §Continuous  Interval  Ratio

Levels of Measurement §Nominal e.g. religion, eye colour §Ordinal e.g. age groups §Interval e.g. temperature ( o C), intelligence §Ratio e.g. temperature (Kelvin), heart rate

Characteristics of measurement levels

The Parameter or the measurement? §Continuous scale Ratio level-DiscreteHeight (m) §Ordinal scaleHeight categories: short, average and tall  Nominal scaleHeight Grouping: 1.7 m 1.2m < 1.50m 1.5m < 1.7m

Identify the Level of Measurement GenderSmokingActivity LevelResting Heart rate 1 = Male 1 = Smoker 1 = Never b.p.m. 2 = Female 2 = Non 2 = x 3 weekly 3 = x2 daily

Exercises §Identify one Qualitative measure and one Quantitative measure useful in your practice. §Identify one parameter from each level of measurement useful in your practice.

Exercises §Identify the level of measurement used in the journal articles chosen §Discuss the appropriateness of that measure §Suggest an alternative Level of Measurement