Stat Unit 3--Winter 2008

Stat Unit 3--Winter 2008 - Central Tendency Wheres the...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Central Tendency Wheres the middle, whats typical in a distribution? Mode Most frequently occurring category Nominal data Median Value of the middle case when distribution is ranked Ordinal data Mean Arithmetic average Sum of case values divided by number of cases Interval/ratio data Variability Once we know something about the center of a distribution, next question is To what degree do cases tend to be different or vary from this measure of the center Number of Children 5 10 15 20 25 30 4 8 1 2 1 6 2 2 4 2 8 3 2 3 6 4 4 4 4 9 5 3 5 7 6 1 6 5 Age Heres a graph of the variability in age of students in a first grade class Variability is very small Heres a graph of EMU students by age More variability than first grader example Number of Students 500 1000 1500 2000 2500 3000 3500 4000 4 8 1 2 1 6 2 2 4 2 8 3 2 3 6 4 4 4 4 9 5 3 5 7 6 1 6 5 AGE Number of People 200 400 600 800 1000 1200 4 8 1 2 1 6 2 2 4 2 8 3 2 3 6 4 4 4 4 9 5 3 5 7 6 1 6 5 + Age Finally, heres a graph of population of Ypsilanti by age There is considerably more variability here Measures of variability depend on the level of measurement of the variable or attribute Nominal data Index of Qualitative Variation (IQV) is available Rarely used Ordinal data Range and interquartile range Interval/ratio data Standard deviation...
View Full Document

Page1 / 25

Stat Unit 3--Winter 2008 - Central Tendency Wheres the...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online