HSS 2381 Chapter 3: Central Tendency, Variability, and Relative Standing
17 Oct 2016
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Chapter 3: central tendency, variability, and relative standing. Characteristics of a data distribution: shape (chapter 2, central tendency, variability. Both central tendency and variability can be expressed by indexes that are descriptive statistics. The mode: the mode is the score value with the highest frequency; the (cid:373)ost (cid:862)popular(cid:863) s(cid:272)ore. The mode: advantages: can be used on any measurement level (including nominal level, easy to co(cid:373)pute(cid:863)- eyeball it, always an actual value in the distribution, so it is easy to understand. Versus mean, it can be just an average and not an actual value: useful when there are 2+ popular(cid:863) s(cid:272)ores (cid:894)i. e. , i(cid:374) (cid:373)ulti(cid:373)odal distri(cid:271)utio(cid:374)s(cid:895) Ignores most information in the distribution: tends to be unstable (i. e. , value varies a lot from one sample to the next) What it is in the sample, is not very representative of what it would be in the bigger picture: some distributions may not have a mode (e. g. , 10, 10, 11, 11, 12, 12)
