Search Results: 'Standard Deviation'
What is Standard Deviation?
The standard deviation is a popular measure of variability. It is used both as a separate entity and as a part of other analyses, such as computing confidence intervals and in hypothesis testing. The... More > standard deviation is the square root of the variance. The population standard deviation is denoted by σ. Like the variance, the standard deviation utilizes the sum of the squared deviations about the mean (SSx). It is computed by averaging these squared deviations (SSX/N) and taking the square root of that average.< Less
Standard Deviation of Portfolio
What is the standard deviation of a portfolio that is invested 40% in stock A and 60% in stock B, given the following information?
Hypothesis Testing for Mean with Known Population Standard Deviation
"A fast food restaurant strives to serve 80 customers per hour during its peak lunch hour. It samples 30 shifts (i.e. 30 peak lunch hours) to determine whether it is meeting this expectation. ... More > The sample mean is 75 customers. The population standard deviation is known to be 10.
1. Set up a null and alternative hypothesis to test whether this sample is falling below expectations.
2. Conduct this hypothesis test at the 5% level of significance.
Sample Size Calculation Using Standard Deviation and Margin of Error
An auditor wants to estimate the mean annual expenditure (across departments) on a particular item. They seek accuracy within a range of $100. The population standard deviation is estimated to be... More > $250. How many departments would they need to survey to achieve this level of accuracy with 95% confidence?< Less
Air Standard Analysis for Internal Combustion Engines
Air-standard analysis treats the fluid flow through the entire engine as air and approxi¬mates air as an ideal gas. In a real engine inlet flow may be all air, or it may be mixed, up with 7%... More > fuel, either gaseous or as liquid droplets, or both. In air-standard analysis, even if all fluid in an engine cycle were air, some error would be introduced by assuming it to be an ideal gas with constant specific heats. At the low pressures of inlet and exhaust, air can accurately be treated as an ideal gas, but at the higher pressures during combustion, air will deviate from ideal gas behavior.< Less
The Rational Statistical Science
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This Tract Book Article describes a Rational Statistics Science which uses a Standard
Deviation of .01%, and a statistical negation test of 1%.