DATA ANALYSIS AND STATISTICS Methodology for Describing and Understanding VARIABILITY

Data consists of SAMPLES, OBJECTS, OBSERVATIONS described by means of one or more VARIABLES

Descriptive DATA ANALYSIS Organising DATA Summarizing DATA

Statistical Inference “Draw conclusions” Hyphothesis Testing

Descriptive DATA ANALYSIS Measure of LOCATION MEAN, MEDIAN Measure of SPREAD, VARIABILITY STANDARD DEVIATION, VARATION RANGE

NORMAL DISTRIBUTION

MEAN k = measured value for observation k N = number of observations

FREQUENCE DISTRIBUTION/ HISTOGRAM

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

25% of all observation is smaller than the LOWER QUARTILE. 75% of all observation is smaller than the UPPER QUARTILE. QUARTILES

STANDARD DEVIATION VARIANCEVARIATION

r = max(x k ) - min(x k ) RANGE The range is the difference between the maximum and the minimum values of a variable

Coefficient of Variation RELATIVE STANDARD DEVIATION SCALE INDEPENDENT

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