CHAPTER 5 Fundamentals of Statistics Quality Control Source: Besterfield, Dale H., Quality Control.

Introduction Definition of Statistics quantitative data football statistics employment statistics science that deals with data collection tabulation analysis presentation decisions concerning quality

Introduction Definition of Statistics descriptive or deductive statistics describe and analyze deals with subject or group inductive statistics uses limited amount of data (sample) important conclusion about a population conclusions or inferences cannot be stated with absolute certainty language of probability

Introduction Collection of Data data collected for quality purposes quality characteristics variables numerical value measurable weight measured in grams attributes no numerical value conforming or not conforming “go/no go gage”

Introduction Collection of Data continuous variables weight of a gray iron casting 11 kg, 11.33 kg or 11.3398 kg accuracy of the measuring instrument discrete variables number of nonconforming rivets in a trailer 0, 3, 5, 10 or 96 continuous variables are measurable discrete data are countable

Introduction Collection of Data Significant figures digits exclusive of any leading zeros 3.69 has three significant figures 36.900 has five significant figures 2700 has four significant figures 22.0365 has six significant figures 0.00270 has three significant figures trailing zeros are counted as being significant leading zeros are not significant

Introduction Collection of Data Significant figures multiplication, division, and exponentiation answer has the same number of significant figures as the number with the fewest significant figures

Introduction Significant figures addition and subtraction with decimal points - final answer can have no more significant figures after the decimal point than the number with the fewest significant figures after the decimal point without decimal points - final answer has no more significant figures than the number with the fewest significant figures

Frequency Distribution Ungrouped Data comprise a listing of the observed values grouped data lumping together of the observed values

Frequency Distribution Ungrouped Data - Histograms

Frequency Distribution Ungrouped Data - Histograms

Frequency Distribution Ungrouped Data in-class example create a relative cumulative frequency histogram given the following frequency distribution

Frequency Distribution Ungrouped Data In class example: next step involves creating a relative cumulative frequency histogram from the following:

Frequency Distribution Grouped Data Determining cell intervals for “grouped data” Collect data and construct a tally sheet Determine the range Determine the cell interval which is the distance between adjacent cell midpoints In general, the number of cells should be between 5 and 20 round down to the nearest odd number n = sample size

Frequency Distribution Grouped Data

Frequency Distribution Grouped Data

SME Computer Aided Design 20 min