复旦生统课件2.pdf

Biostatistics: Methods and Applications Prof. Weidong Tian Prof. Hong Zhang Tel: 021 Email: weidong.tian@ Office: 2320 East Guanghua Building Review of Last Week’s talk • Mean, Median, Variance • Frequency Table, Histogram, Boxplot • Probability theories and Bayes’ rule Descriptive statistics • Descriptive statistics provide a way to summarize data from a sample or a population • DSs illustrate the central tendency, variability and shape of a set of data • Central tendency describes the location of the middle of the data • Variability is the extent values are spread above and below the middle values • The shape of data has to do with the frequencies of the values of observations Mean, median and Variance 55 55 .. .. 22 variance = 0.335 22 variance = 0.042 00 00 ..