STAT 100 Lecture Notes - Lecture 10: Percentile, Quartile, Standard Deviation

• School: Simon Fraser University
• Department: Statistics
• Course: STAT 100
• Professor: Gamage Perera

Document Summary

The 68-95-99. 7 rule know for exam. Using the standard normal table on page 668. We now have a toolbox of graphical and numerical methods for describing distributions. What is more, we have a clear strategy for exploring data on a single quantitative variable. Now we add one more step to this strategy: sometimes, the overall pattern of a large number of observations is so regular that we can describe it by a smooth curve. Example: here is a histogram of vocabulary scores of 947 seventh graders. The smooth curve drawn over the histogram is a mathematical model for the distribution. A density curve is a curve that: is always on or above the horizontal axis: has an area of exactly 1 underneath it. A density curve describes the overall pattern of a distribution. The area under the curve and above any range of values on the horizontal axis is the proportion of all observations that fall in that range.