Test Scores: Variance & Maximum Mark

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SUMMARY

The discussion clarifies that the sample variance of test scores can exceed the maximum mark of 100. Using the example of test scores 0 and 100, the calculated sample variance is 5000, while the sample mean is 50. The sample standard deviation, derived from this variance, is 70, which does not exceed the maximum mark. Therefore, while variance can exceed the maximum score, the standard deviation remains bounded by it.

PREREQUISITES
  • Understanding of sample variance and standard deviation
  • Familiarity with statistical notation and formulas
  • Basic knowledge of mean calculation
  • Concept of bounded scores in statistical analysis
NEXT STEPS
  • Study the derivation of sample variance and its properties
  • Learn about the implications of variance exceeding maximum values
  • Explore the relationship between variance and standard deviation
  • Investigate real-world applications of variance in educational assessments
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Students, educators, statisticians, and data analysts interested in understanding the properties of variance and standard deviation in test score analysis.

Ted123
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Say we have a sample of test scores, all marked between 0 and 100.

Does the sample variance have to be less than or equal to the maximum mark 100 or can it exceed this?
 
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It can exceed it: say your test scores are 0 and 100. Then the sample mean is 50. The sample variance equals

[tex]\frac{1}{n-1}\sum_{i=1}^n{(X_i-\overline{X_n})^2}=5000[/tex].

You probably mean the sample standard deviation... In this example, it is 70. I don't think it can exceed 100...
 

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