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Monthly Archives: September 2011
Comparing Growth Charts
Suppose both an 8year old boy and a 10year 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
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
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 collegelevel work”. … Continue reading
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
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
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
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
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
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 WalMart Stores, … Continue reading
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 →