Standard deviation of a new sample

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SUMMARY

The discussion centers on calculating the standard deviation of a remaining sample of resistors after forming a subgroup. The original set has a mean of 100 ohms and a standard deviation (SD) of 20 ohms, while the subgroup has a mean of 100 ohms and an SD of 5 ohms. To accurately determine the SD of the remaining sample, it is essential to know the total number of resistors in the original set and how many were included in the subgroup. The conclusion is that the SD of the remaining sample will likely be greater than 20 ohms due to the removal of resistors closest to the mean.

PREREQUISITES
  • Understanding of standard deviation and its calculation
  • Knowledge of statistical sampling techniques
  • Familiarity with basic concepts of mean and variance
  • Ability to perform calculations involving populations and subgroups
NEXT STEPS
  • Learn about the formula for calculating the standard deviation of combined samples
  • Study the concept of variance and its relationship to standard deviation
  • Explore statistical sampling methods and their implications on data analysis
  • Investigate the impact of removing data points on overall statistical metrics
USEFUL FOR

This discussion is beneficial for statisticians, data analysts, and anyone involved in quality control or data sampling who needs to understand the implications of subgroup analysis on overall data metrics.

seidjeep
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Hello all,

I am trying to figure out the following question with no luck: I have a box of resistors, mean 100 ohms and SD of 20 ohms. I form a subgroup of these resistors with mean of 100 ohms and SD of 5 ohms. Find the standard deviation of the remaining sample. The question does not give starting number of resistors. I'm guessing the standard deviation would be greater than the original 20 ohms since we removed all the resistors closest to the mean. Any clues about how to get this started would be awesome. Thanks.
 
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The key to this is knowing how many in the original set and how many have been set aside into the subset. It would be a straightforward calculation as a function of these parameters.
 

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