Tag Archives: number of samples

Secrets of Good Correlations

If you’ve ever seen a correlation coefficient, you’ve probably looked at the number and wondered, is that good? Is a correlation of -0.73 good but not a correlation of +0.58? Just what is a good correlation and what makes a … Continue reading

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Ten Fatal Flaws in Data Analysis

1. Where’s the Beef? In a way, the worst flaw a data analysis can have is no analysis at all. Instead, you get data lists, sorts and queries, and maybe some simple descriptive statistics but nothing that addresses objectives, answers … Continue reading

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It was Professor Plot in the Diagram with a Graph

You probably were taught how to graph data in high school. Depending on your work, you may frequently plot data yourself or look at graphs prepared by others. Even if you don’t use graphs on your job, you may run … Continue reading

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Samples and Potato Chips

Samples are like potato chips. You’re never satisfied with just one. Every one you take makes you want more. And you’re never sure you’ve had enough until you’ve had way too many.   Betcha Can’t Take Just One One observation. … Continue reading

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Purrfect Resolution

No matter what their area of expertise, statisticians are asked certain questions with such predictability that it borders on the deterministic. No question is asked more often than: How many samples do I need? Most statisticians wish they could answer … Continue reading

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30 Samples. Standard, Suggestion, or Superstition?

If you’ve ever taken any applied statistics courses in college, you may have been exposed to the mystique of 30 samples. Too many times I’ve heard statistician do-it-yourselfers tell me that “you need 30 samples for statistical significance.” Maybe that’s … Continue reading

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