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Published byAshlee Butler Modified over 8 years ago
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DATA ANALYSIS AND STATISTICS Methodology for Describing and Understanding VARIABILITY
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Data consists of SAMPLES, OBJECTS, OBSERVATIONS described by means of one or more VARIABLES
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Descriptive DATA ANALYSIS Organising DATA Summarizing DATA
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Statistical Inference “Draw conclusions” Hyphothesis Testing
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Descriptive DATA ANALYSIS Measure of LOCATION MEAN, MEDIAN Measure of SPREAD, VARIABILITY STANDARD DEVIATION, VARATION RANGE
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NORMAL DISTRIBUTION
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MEAN k = measured value for observation k N = number of observations
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FREQUENCE DISTRIBUTION/ HISTOGRAM
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MEDIAN The median of a variable/object estimates the centre of the data distribution. =, N odd, N even The MEDIAN is a more robust measure than the MEAN for location
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25% of all observation is smaller than the LOWER QUARTILE. 75% of all observation is smaller than the UPPER QUARTILE. QUARTILES
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STANDARD DEVIATION VARIANCEVARIATION
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r = max(x k ) - min(x k ) RANGE The range is the difference between the maximum and the minimum values of a variable
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Coefficient of Variation RELATIVE STANDARD DEVIATION SCALE INDEPENDENT
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Used for revealing systematic variation with time, e.g, CONTROL CHART QUALITY CONTROL FOR MONITORING LABORATORY ANALYSIS AND INDUSTRIAL PROCESSES (TRENDS/DEVIATION), STATISTICAL PROCESS CONTROL (SPC) TIME SERIES PLOT
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