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Browse High School Statistics
Stars indicate particularly interesting answers or good places to begin browsing.

Selected answers to common questions:
    Mean, median, mode, range.
    Statistics glossaries.
    Weighted averages.

Averages with Examples [10/17/2001]
My teacher has explained three ways to figure out averages, kind of like weighted averages, but without the weight...

Calculating Breast Cancer Survival Rates [06/30/2003]
Survival of a group of breast cancer patients is 100 at year 0, 100*X at year 1, 100*X*X at year 2, 100*X*X*X at year three and so on to year 10. How do I find the nth year survival?

Chi-Square Test [04/24/2002]
Four chiropractors examine a patient... I have calculated the number of times the chiropractors agree for any combination of 2, 3, and all 4; I need to compare this finding to that of chance probability of agreement.

Grade and Test Averages [12/02/2001]
In a class of 21 students the average score on a math test was 77%. If Suzie got 95% and Jack got 78%, find the average grade of the other 19 students.

Measures of Dispersion [6/30/1996]
What are the different characteristics of: Range, Mean Absolute Deviation, Standard Deviation, Variance, Quantiles (percentile, decile, quartiles), covariance?

Questions About Standard Deviation [9/20/1995]
Why does a standard deviation take the square root of the average of the sum of the squared differences between X and X mean instead of the average of the absolute value differences? What is the reasoning behind dividing by n vs. n-1 in the population versus sample standard deviations?

Sample and Population Standard Deviation [03/03/2001]
What letters represent theoretical and 'real' standard deviation, mean, and variance?

Stem and Leaf and Scatter Plots [10/13/1998]
Information on stem and leaf plots and scatter plots.

Using the Range to Find Outliers [09/11/2001]
How can you use the range of a set of numbers to determine whether any of the observations were outliers?

Weighted Averages [11/02/1998]
Can you explain the concept of weighted averages, with examples?

20 Golf Players [04/11/1997]
How do you set up four teams such that the variance in the average team handicap is no more than one or two?

Analyzing Survey Results [05/04/2000]
How can I determine a ranking of priority (1st, 2nd, 3rd, etc.) for the results of a satisfaction survey that asked people to rank, in order of importance, seven factors?

Applications of Arithmetic, Geometric, Harmonic, and Quadratic Means [11/22/2006]
How do I choose what sort of mean to calculate for a given set of data?

Are Two Formulas for Finding Standard Deviation the Same? [10/29/2007]
My statistics text gives a shortcut formula for calculating sample SD as the square root of [(the sum of x^2) minus (the sum of x)^2/n all divided by n-1]. Is this really just another form of the full formula?

Arithmetic vs. Geometric Mean [03/27/2001]
When is it appropriate to use the arithmetic mean, and when the geometric mean?

Arrangements of Letters [09/14/1999]
In how many ways can the letters in UNUNSUAL be arranged? For those arrangements, how many have all 3 U's together?

Average of Ratios vs. Ratio of Averages [10/24/2003]
We currently calculate 'Average dollars per square foot' as the ratio of the average price divided by the average square footage of all the homes in the list. It seems to me that it should be calculated as the average of the price-per-square-foot ratio of each house. Can you think of any reason why the ratio of the averages would be more useful than the average of the ratios?

Average Radial Distance of Points within a Circle [03/26/2003]
I'm trying to determine the average value of a circular/radial gradient that is at full value (white, call it 100% brightness) in the center, and drops in a linear fashion to zero (black, call it 0% brightness) at the radius.

Averaging Averages [11/09/1999]
How can I average the results of a survey sent to 5 different departments if I only have averages from each department?

Averaging Kelly's Test Scores [01/07/2002]
Kelly's average score on 4 tests is 85.5. The average of her 3 highest scores is 87, and her two lowest scores are the same as each other. What is the average of her two highest test scores?

Bar Graphs and Histograms [04/30/2008]
What is the difference between a bar graph and a histogram? What are the similarities? Which graph explains more details?

Bar Graphs vs. Histograms [09/05/2002]
What is the difference between bar graphs and histograms?

Batting Averages [05/07/1999]
How do you calculate batting averages? Do you have to average the new hit into all the previous hits?

Bayesians and Frequentists [08/21/2001]
What is the difference between Bayesian and "regular" statistics?

Benford's Law [08/06/1998]
What is Benford's law?

Best Line Fit: Least Squares [03/23/1997]
What is least squares fitting? How exactly does one do it?

Biased and Unbiased Surveys [11/05/2008]
The Tri-State Soccer League is conducting a survey to determine if the players want to change the style of soccer shirt. If they randomly survey all players who wear size large shirts, is the survey biased or unbiased? I'm not sure what those two words mean.

Binomial and Normal Distribution [06/09/1999]
Could you please tell me the difference between normal approximation to binomial distibution and normal distribution?

Binomial Distribution [8/25/1996]
The mean life of a certain television tube is 1200 hours with a standard deviation of 200 hours... The probability that three machines will be in use on any one day is 0.8,0.7 and 0.6 respectively.

Binomial Experiments [09/05/2003]
How can I explain the binomial distribution to my six grade math class?

Box and Whisker Plots [02/13/2000]
Can you explain how to make and use box and whisker plots?

Box and Whisker Plots [05/18/2000]
If there is an odd number of points in a data set, is the median considered to be part of the subgroup used to find the upper (or lower) quartile?

Calculating a Grade Average [08/15/1999]
How can I figure out my average if some things are worth more than others?

Calculating and Interpreting Expected and Chi-Square Tables [04/10/1998]
How do you calculate the expected frequency and chi-square value of a 3- by-3 table?

Calculating and Interpreting Z-Scores [12/13/2005]
Please help me by providing a step-by-step process for calculating the z-score, or standard score.

Calculating Average Starting Time [06/23/2003]
How do you average a series of starting times to get the average starting time? Say 9:30a.m., 10:15a.m., 11:45a.m., 1:30p.m., and 11:30a.m.

Calculating a Weighted Average Grade [05/05/2000]
What is the grade if the following make up the final grade: 45% = 3 tests (85, 78, 92), 25% = final (94), 15% = project (91.9), 15% = 3 case questions each worth 25 points (25, 25, 23.5)?

Calculating Percentage Errors [02/20/1999]
How do you calculate percent error from a set of data that includes predicted values and observed values?

Calculating Percentage of Errors [03/21/2002]
You have items to be picked off a shelf every day. You pick one item a day and check it against the order. You wish to asign a percentage to the error in wrong items and/or number of items.

Calculating Percentile Rank [04/30/2009]
When calculating percentile rank, if more than one data value matches the number you are calculating, why do you count only half of them?

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