02-Basic Statistics Review - class

# 02-Basic Statistics Review - class - Basic Statistics...

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Unformatted text preview: Basic Statistics Review Types of Data Basic Statistics REVIEW William C. Hurst FDST 4090/6090 (2009) ATTRIBUTE VARIABLE FDST 4090/6090 W.C. Hurst 2009 Population vs. Sample Population (N) (N) Sample (n) subgroup or (n) subset of a population Number of Central Tendency X (x-bar) - mathematical center point in a group of (xvalues Number of X= FDST 4090/6090 W.C. Hurst 2009 i =1 xi n n 3,1,5,10,16 35 = =7 5 5 FDST 4090/6090 W.C. Hurst 2009 Central Tendency (cont) (mo) most common number in data set Sample: 1, 3, 7, 4, 7, 8, 7, 2 = ~ Measure of Dispersion Variability 1. 2. ( x ) middle value in ranked numerical order of data Sample: 1, 3, 10, 16, 5 = 1, 3, 5, 10, 16 3. FDST 4090/6090 W.C. Hurst 2009 FDST 4090/6090 W.C. Hurst 2009 UGA FDST 4090/6090 - (c) W.C. Hurst 2009 Basic Statistics Review Range (R) Range ( R ) = Sample: 3, 5, 10, 1, 16 R = 16-1 = 15 16- Variance (s2) s 2 = i =1 ( xi - X ) 2 n -1 n FDST 4090/6090 W.C. Hurst 2009 FDST 4090/6090 W.C. Hurst 2009 Standard Deviation Sample: 3, 5, 1, 16, 10 X=7 n=5 s= 2 2 Frequency Distribution 2 s= 2 i =1 ( xi - X ) n -1 2 n (3 - 7) + (5 - 7) + (1 - 7) + (16 - 1) + (10 - 7) 5 -1 2 Suppose a QC technician was asked by the QA manager to determine the mean weight and variability of carrot stick packages coming off the end of a production line. After removing and weighing 30 packages, the following results were obtained. Calculate the mean, range and standard deviation of this data set. SEE WORKSHEET xi 23g 24g 25g 26g TOTAL Fi (frequency) 11 6 5 8 s = 6.04 FDST 4090/6090 W.C. Hurst 2009 FDST 4090/6090 W.C. Hurst 2009 Sources of Variation No two things exactly alike! Categories of Variation FDST 4090/6090 W.C. Hurst 2009 FDST 4090/6090 W.C. Hurst 2009 UGA FDST 4090/6090 - (c) W.C. Hurst 2009 Basic Statistics Review Types of variation Common cause Random, natural, due to chance Management must change process to improve Special cause (unnatural) Assignable cause Common Cause Variability On-line personnel Onmust find and eliminate FDST 4090/6090 W.C. Hurst 2009 FDST 4090/6090 W.C. Hurst 2009 Special Cause Variability Examples of Variability COMMON CAUSE SPECIAL CAUSE Slight variance in machine Faulty machine set-up set- FDST 4090/6090 W.C. Hurst 2009 FDST 4090/6090 W.C. Hurst 2009 UGA FDST 4090/6090 - (c) W.C. Hurst 2009 ...
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## This note was uploaded on 06/15/2010 for the course FDST 4080 taught by Professor Pegg during the Spring '10 term at UGA.

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