STAT 213 Lecture 5: lec5

• School: University of Calgary
• Department: Statistics
• Course: STAT 213
• Professor: Anatoliy Swishchuk

Document Summary

The 68 95 99. 7 rule. We have already known about graphical (lectures 1-2) and numerical (lecture 3-4) tools for describing distributions. We also know how to explore data on a single quantitative variable. Sometimes the overall pattern of a distribution can often be described compactly by a smooth curve. The smooth curve drawn through the histogram (figure 1. 19) gives a compact discription of the overall pattern. We draw a smooth curve through a histogram to describe the shape of the distribution without the lumpiness of the histogram. The curve is a mathematical model (idealized mathematical descrip- tion) for the distribution. Area of the bars in histograms=proportions of the. To make such curves easier to compare for di erent distribu- tions, we adjust the sacle so that the total area under the curve is exactly 1. Areas under the curve then represent proportions of the observa- tions. The curve is then a density curve.