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| courses:ast201:3 [2023/10/22 05:34] – [1. Accuracy and precision] asad | courses:ast201:3 [2023/10/22 05:37] (current) – [2. Population and sample] asad | ||
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| - | In this example, the velocities of 50 stars perpendicular to the Galactic plane are plotted as a bar-chart histogram. The stars are divided into two sets: 25 stars are iron-rich and the other 25 stars are iron-poor. The iron-poor stars have a greater dispersion of velocities as evident from the plot. The mean and the standard deviation are shown as vertical lines and shades, respectively. | + | In this example, the velocities of 50 stars perpendicular to the [[uv:mw|Galactic plane]] are plotted as a bar-chart histogram. The stars are divided into two sets: 25 stars are iron-rich and the other 25 stars are iron-poor. The iron-poor stars have a greater dispersion of velocities as evident from the plot. The mean and the standard deviation are shown as vertical lines and shades, respectively. |
| Standard deviation is sometimes better than variance in describing physical phenomena because $\sigma$ has the same unit as $\mu$, but the units are squared in $\sigma^2$ statistic. In this example, the variance among iron-rich stars is $57.25$ km$^2$ s$^{-2}$ whereas the standard deviation is $7.57$ km s$^{-1}$. | Standard deviation is sometimes better than variance in describing physical phenomena because $\sigma$ has the same unit as $\mu$, but the units are squared in $\sigma^2$ statistic. In this example, the variance among iron-rich stars is $57.25$ km$^2$ s$^{-2}$ whereas the standard deviation is $7.57$ km s$^{-1}$. | ||
courses/ast201/3.1697974455.txt.gz · Last modified: 2023/10/22 05:34 by asad