Presentation on theme: "Levels of Measurement Nominal measurement Involves assigning numbers to classify characteristics into categories Ordinal measurement Involves sorting objects."— Presentation transcript:
Levels of Measurement Nominal measurement Involves assigning numbers to classify characteristics into categories Ordinal measurement Involves sorting objects based on their relative standing on an attribute
Levels of Measurement (cont.) Interval measurement Occurs when objects are rank- ordered on a scale that has equal distances between points on the scale (no inherent starting point) Ratio measurement Occurs when there are equal distances between score units and there is a rational, meaningful zero (with inherent starting point) 90 cm is twice as long as 45 cm with absolute zero point 90°F is not twice as hot as 45°F with arbitrary zero point Scores?
Frequency Distributions A systematic arrangement of numeric values on a variable from lowest to highest, and a count of the number of times each value was obtained Frequency distributions can be described in terms of: ◦ Shape ◦ Central tendency ◦ Variability
Distribution of Values: Central Tendency Index of “typicalness” of set of scores that comes from center of the distribution Mode— the most frequently occurring score in a distribution 2 3 3 3 4 5 6 7 8 9 Mode = 3
Distribution of Values: Central Tendency (cont.) Median— the point in a distribution above which and below which 50% of cases fall 2 3 33 4 5 6 7 8 9 Median = 4.5 Mean— equals the sum of all scores divided by the total number of scores 2 3 3 3 4 5 6 7 8 9 Mean = 5.0