4 articles trouvés pour ce sujet.
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Sample variance |
2010-01-25 |
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shodhan pose la question :
A series of 100 measurements of a physical quantity have been made that show a random fluctions characterized by a sample variance of 2% of teh mean value. If the series is lengthed to 1000 measurements made under the same conditions, estimates the sample variance of the larger set of data.
Robert Dawson lui répond. |
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Sample variance: inches to centimeters |
2008-09-22 |
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Anita pose la question :
The average height of a sample of basketball players is 6 feet, 2 inches or 74 inches.
The standard deviation of this sample of players is 4 inches. If each person's height were to be multiplied by 2.54, what would be the value of the resulting sample variance?
Harley Weston lui répond. |
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Sample variance |
2005-08-17 |
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Rosalie pose la question :
To give an unbiased estimate of the population variance, the denominator of the sample variance should be (n-1) instead of n. I tried to convince myself by comparing the population variance and sample variance (with denominator n and n-1):
Penny Nom lui répond. |
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Sample variance |
2000-04-16 |
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Jonathan Freeman pose la question :
I was just reading your article entitled "A Note on Standard Deviation" I'm now teaching a unit on s.d. and my students were wondering why one uses a denominator of n for a population and n-1 for a sample. I saw in your article that this is because "[the quantity] tends to underestimate sigma... and other technical reasons." To which my students again asked... "Why?" Could you please elaborate a bit on the "other technical reasons" perhaps in terms a high school senior (or their teacher...) could understand?
Harley Weston lui répond. |
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