Measurement Statistics

Measurement Scales and Types of Data

MeasurementWhile people measure things casually in daily

life, research measurement is more precise and controlled.

Variables being studied in research may be classified as objects or as properties.– Objects include tangible items such as furniture,

laundry detergent, people or automobiles.– Properties are the characteristics of the object. A

person's physical properties include weight, height etc., and his psychological properties are attitudes and intelligence.

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An event is measured in terms of its duration;

For duration, one measures the number of hours and minutes recorded.

Measurement

MeasurementFor what happened, one uses some system

to classify types of activities that occurred.Measurement typically uses some sort of

scales to classify or quantify the data collected.

There are four types of scales. In increasing order of power, they are nominal, ordinal, interval, and ratio.

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Nominal – Classify into categories – no order, distance, or natural origin

Example: personality type, religion, gender Ordinal – Order objects along a dimension (ranking) but

no distance or natural origin Example: Top 10 movies

Interval – Meaningful distances between rankings: ordered, distance, but no natural origin

Example: thermometer Ratio – Interval with true zero point (most precise):

ordered, distance, natural origin Example: height, weight, age, length

Measurement

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MeasurementA. Store Customers:Nominal – Group them by race, ethnic

background, married or single status, etc.Ordinal – Rank them as very frequent

buyers, frequent buyers, infrequent buyers.

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MeasurementInterval – Customer Satisfaction on

different points interval i.e.

Ratio – Average size of monthly purchases

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MeasurementB. Voter Attitudes Nominal – grouped as PML(N), PPP, PTI, and

others; Ordinal – Rank of candidates in order of

preference; Interval – Likert – type scale. Most likely to win,

likely to win, neutral, less likely to win, cannot win Ratio – Count of votes for various candidates in

each district.

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MeasurementC. Common Stock Preference

Nominal – Industry classification of stocks;

Ordinal – Rank order of preference stocks

as your preference for them;

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MeasurementInterval – Rating of preference for the

stock by converting the results of a paired comparison rating into presumed interval scale;

Ratio – Six-month changes in price of various preferred stocks.

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Characteristics of Good Measurement

Three major criteria for evaluating a measurement tool are: validity, reliability, and practicality.– Validity is the extent to which a test measures

what we actually wish to measure.– Reliability has to do with the accuracy and

precision of a measurement procedure. – Practicality is concerned with a wide range of

factors of economy, convenience, and interpretability

Types of Data

Quantitative – things you measure Examples: (age, time, scores, etc.) How much does a book weigh?

Qualitative – things you categorize Examples: (gender, race, class standing, etc.) What color is the book?