Monthly Archives: September 2011

Comparing Growth Charts

Suppose both an 8-year old boy and a 10-year old boy are 54 inches tall (four feet six inches). Physically they are of the same heights. But a better way to compare is to find out where each boy stands … Continue reading

Posted in Descriptive statistics, Normal Distributions, Statistics | Tagged , , , , , , , , | Leave a comment

An Example of a Normal Curve

One way to estimate probabilities is to use empirical data. However, if the histogram of the data shapes like a bell curve (or reasonably close to a bell curve), we can use a normal curve to estimate probabilities. All we … Continue reading

Posted in Normal Distributions, Statistics | Tagged , , , , | 2 Comments

A Student’s View of the Normal Distribution

In my teaching, I always strive to encourage students to look at statistics from a practical point of view. In a recent class period covering the normal distribution, I indicated that data values more than 3 standard deviations away from … Continue reading

Posted in Commentary, Descriptive statistics, Normal Distributions, Statistics | Tagged , , , , , | 3 Comments

Interpreting ACT Scores

The ACT is a standardized test that is used for college and university admissions in the United States. According to their web site, the ACT test “assesses high school students’ general educational development and their ability to complete college-level work”. … Continue reading

Posted in Descriptive statistics, Statistics | Tagged , , , , , , | 1 Comment

Are Small City Drivers Safer than Large City Drivers?

To answer this question, we focus on cities with population of 100,000 and up. In this group of cities, are the drivers in the smaller cities safer than the drivers in large metropolitan areas? A recent report from Allstate Insurance … Continue reading

Posted in Descriptive statistics, Regression, Statistics | Tagged , , , , , , | Leave a comment

The Safest Driving City in America

Which city in America has the worst drivers? When I asked this questions, many people guessed New York or Los Angeles. How about the city with the safest drivers? According to a recent report released by The Allstate Insurance Company, … Continue reading

Posted in Descriptive statistics, Statistics | Tagged , , , , , , , , , , | 1 Comment

Choosing a High School

Many parents try to find the best high school for their children. Many variables are usually involved in choosing a school. One criterion is to look at successes of the graduates of a school. One measure of success may be … Continue reading

Posted in Descriptive statistics, Statistics | Tagged , , , , , , , , , | Leave a comment

LA Rainfall Time Plot

In a previous post, we had an elementary look at the seasonal rainfall data in Los Angeles, California, using graphs (histograms) and numerical summaries to describe the data. The rainfall data were collected over time (total rainfall in inches over … Continue reading

Posted in Descriptive statistics, Statistics | Tagged , , , , , , | Leave a comment

When Bill Gates Walks into a Bar

The mean of a data set is obtained by summing the data elements in the data set and divided by the total number of data elements (what most people think of as average). The median of a data set is … Continue reading

Posted in Descriptive statistics, Statistics | Tagged , , , , , , , , | 3 Comments

Fortune Global 500

The Fortune Global 500 is a list of the largest 500 companies worldwide ranked by revenue. The list is compiled and published annually by Fortune magazine. In the 2011 list for Fortune Global 500, the top company is Wal-Mart Stores, … Continue reading

Posted in Descriptive statistics, Statistics | Tagged , , , , , | Leave a comment