FANR 3000 1st Edition Lecture 2 Outline of Last Lecture I Data Definitions II Types of Data Outline of Current Lecture I Precision and Accuracy II Types of error bias III Describing and graphing data Current Lecture I Precision and Accuracy a Accuracy the closeness of a measured value to the known true value b Precision the closeness of 2 or more measurements to each other i Independent of accuracy These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute II III Types of error bias a Mistakes gross errors incorrect measurements due to carelessness i Reading the wrong number ect b Systematic error bias errors of the same size and magnitude with each subsequent measurement i Bent compass needle ect ii If the magnitude of error is known accuracy can be improved by a correction adjustment factor c Random error always present in a measurement i Unpredictable fluctuations in the readings due to equipment weather or reader ii Difficult to fix since errors vary in magnitude Describing and graphing data a Two primary methods of describing data i Graphically histograms bar graphs pie charts scatter plots maps ect ii Numerically means ranges variability confidence intervals ect b Histograms i Frequency quantitative qualitative 1 1 n number of observations in each variable class ii Relative frequency quantitative qualitative 1 0 1 fraction of the total observations in each variable class iii Cumulative frequency quantitative c d e f g 1 1 n the frequency of a variable class plus the frequencies of the classes below it iv Cumulative relative frequency quantitative 1 0 1 the relative frequencies plus the relative frequencies of the classes below it Ogive linear version of cumulative histograms Bar graphs associated with categories qualitative Pie chart qualitative relative frequency chart Line graph x y causation change in variable over time X Y chart not a continuous sample change in variable in relation to another