CHEM 2364 : Chem 2001 Exam 1 Study Guide
Document Summary
Qualitative data- descriptions, data can be observed but not measured: colors, textures, smells, qualitative quality. Quantitative data- numbers, data which can be measured. The mean (average) defines the center of the gaussian distribution: wide distribution (broad curves)- poor precision, narrow distribution (sharp curves)- good precision, also denoted by mu ( ) The width of the gaussian distribution is defined by standard deviation: higher standard dev (s) value indicates a wider distribution and poor precision, measure of random error, also denoted by sigma ( , variance = s^2. Precision is measured by the standard deviation from the mean. Accuracy can be measured by the percent error of the experiment (true value experimental value)/(true value) x 100. Random error- caused by uncontrollable fluctuations in variables that affect experimental results: air fluctuations from students opening and closing door throughout experiment. Systematic error- instrumental, methodological, or personal mistakes, causing lopsided data that consistently deviated in one direction from the true value.
