StatisticsBasic StatisticsChapter OneStatisticsSTATISTICS AND QUALITYQuality is not an art but a science with proven methods.These proven methods require an understanding of some of the key concepts of statistics. It is also well proven that quality improvement efforts in industry have statistics as their foundation.lmost all of the quality advocators are statisticians and they used the concepts of statistics as a fundamental building block in quality and process improvements. The use of statistics in quality involves the divisions of collecting! tabulating! analysing! interpreting and presenting the numerical data.StatisticsThe SPC approachis designed to identify underlying cause of problems which cause process variations that are outside predetermined tolerances and to implement controls to fi" the problem.StatisticsThe SPC steps#asic approach$wareness that a problem e"ists.%etermine the specific problem to be solved.%iagnose the causes of the problem.%etermine and implement remedies.Implement controls to hold the gains achieved by solving the problem.StatisticsSPC requires the use of statisticsQuality improvement efforts have their foundation in statistics.Statistical process control involves thecollectiontabulationanalysisinterpretationpresentation of numerical data.StatisticsStatistic types Deductive statistics describe a complete data set Inductive statistics deal with a limited amount of dataStatisticsStatistics&O&'(TIO)&arameters$, , 2S*&(+Statistics$ "! s! s,InferentialStatisticsDeductiveInductiveStatisticsTypes of data`-ariables data . quality characteristics that are measurable values.Measurable and normally continuous; may take on any value.ttribute data . quality characteristics that are observed to be either present or absent! conforming or nonconforming. Countable and normally discrete; integerverage/Standard deviation StatisticsStatisticsDescriptive statistics*easures of Central Tendency%escribes the center position of the data*ean *edian*ode*easures of %ispersion%escribes the spread of the data0ange -ariance Standard deviationStatisticseasures of ce!tra" te!de!cy# Meanrithmetic mean " / Swhere "i is one observation! means 1add up what follows2 and ) is the number of observationsSo! for e"ample! if the data are $ 3!,!4!5!6, the mean is 738,848586,9:4 / ,;:4 / 4.