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Unformatted text preview: Types of data Some discrete data summaries Some continuous data summaries Some numerical summaries Boxplots MATH1005 Statistics Lecture 2 M. Stewart School of Mathematics and Statistics University of Sydney Types of data Some discrete data summaries Some continuous data summaries Some numerical summaries Boxplots Outline Types of data Discrete data Continuous data Some discrete data summaries Frequency table Some continuous data summaries Histograms Some numerical summaries Median Quartiles Boxplots Types of data Some discrete data summaries Some continuous data summaries Some numerical summaries Boxplots Discrete data • When data is such that it can only take values in a set of isolated points on the real line, we say the data is discrete . • The classic example is when the data consist of counts . • Consider dataset 1 in the text book: counts the number of cells in each of a regular 20by20 grid of squares: Types of data Some discrete data summaries Some continuous data summaries Some numerical summaries Boxplots Dataset 1 Phipps & Quine ted suspension of yeast cells was spread on a microscopic slide divided into 400 s of equal areas. The number of cells per square gave a sample of 400 counts nt (1907)). 2 4 4 4 5 2 4 7 7 4 7 5 2 8 6 7 4 3 4 Types of data Some discrete data summaries Some continuous data summaries Some numerical summaries Boxplots Continuous data • In contrast to discrete data, continuous data can (in principle) take any value in a (given, known, possibly in nitelengthed) interval. • In fact, such data is generally always rounded to a certain no. of decimal places and so is in fact discrete in that sense; however, the quantity represented by such data is continuous in nature. This is the fundamental di erence. • The discrete or continuous nature of the quantities represented by the data determine what kind of probability model we shall posit for the data. Discrete and continuous probability models are fundamentally di erent, as we shall see. Types of data Some discrete data summaries Some continuous data summaries Some numerical summaries Boxplots Dataset 3 Phipps & Quine 3. Measurements (in mm) of diameters of rivet heads produced by the same machine. 13.39 13.43 13.54 13.64 13.40 13.55 13.40 13.26 13.42 13.50 13.32 13.31 13.28 13.52 13.46 13.63 13.38 13.44 13.52 13.53 13.37 13.33 13.24 13.13 13.53 13.53 13.39 13.57 13.51 13.34 13.39 13.47 13.51 13.48 13.62 13.58 13.57 13.33 13.51 13.40 13.30 13.48 13.40 13.57 13.51 13.40 13.52 13.56 13.40 13.34 13.23 13.37 13.48 13.48 13.62 13.35 13.40 13.36 13.45 13.48 13.29 13.58 13.44 13.56 13.28 13.59 13.47 13.46 13.62 13.54 13.20 13.38 13.43 13.35 13.56 13.51 13.47 13.40 13.29 13.20 13.46 13.44 13.42 13.29 13.41 13.39 13.50 13.48 13.53 13.34 13.45 13.42 13.29 13.38 13.45 13.50 13.55 13.33 13.32 13.69 13.46 13.32 13.32 13.48 13.29 13.25 13.44 13.60 13.43 13.51 13.43 13.38 13.24 13.28 13.58 13.31 13.31 13.45 13.43 13.44 13.34 13.49 13.50 13.38 13.48 13.43 13.37 13.29 13.54 13.3313....
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This note was uploaded on 08/28/2011 for the course SCIENCE 1002 taught by Professor Pu during the Three '11 term at University of New South Wales.
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