Generally not without further reason. Extreme values are often called outliers. Eliminating unusually high values will lower the standard deviation. You may want to calculate standard deviations with and without the extreme values to identify their impact on calculations. See related link for additional discussion.
Three standard deviations refer to a statistical measure that indicates the range within which approximately 99.7% of data points in a normal distribution fall. In other words, if you have a dataset with a mean (average) value and a standard deviation, three standard deviations above and below the mean encompass nearly all the data points, highlighting the spread and variability of the data. This concept is often used in quality control and statistics to identify outliers or extreme values.
The reason the standard deviation of a distribution of means is smaller than the standard deviation of the population from which it was derived is actually quite logical. Keep in mind that standard deviation is the square root of variance. Variance is quite simply an expression of the variation among values in the population. Each of the means within the distribution of means is comprised of a sample of values taken randomly from the population. While it is possible for a random sample of multiple values to have come from one extreme or the other of the population distribution, it is unlikely. Generally, each sample will consist of some values on the lower end of the distribution, some from the higher end, and most from near the middle. In most cases, the values (both extremes and middle values) within each sample will balance out and average out to somewhere toward the middle of the population distribution. So the mean of each sample is likely to be close to the mean of the population and unlikely to be extreme in either direction. Because the majority of the means in a distribution of means will fall closer to the population mean than many of the individual values in the population, there is less variation among the distribution of means than among individual values in the population from which it was derived. Because there is less variation, the variance is lower, and thus, the square root of the variance - the standard deviation of the distribution of means - is less than the standard deviation of the population from which it was derived.
Because the standard deviation is based on the square root of the sum of the squares of the deviations, and, as a result, the sum of the squares of the deviations puts more weight in outliers than does a simple arithmetic mean.Note: I wrote this and then had second thoughts, but I'm keeping it in so that someone with more knowledge can weigh in (pun intended). I'm not certain how the arithmetic mean factors into the question. I think the questioner, and definitely this answerer, is confused.
It depends entirely on the variance (or standard error).
Yes, that's true. The range, which is calculated as the difference between the maximum and minimum values in a dataset, only considers these two extreme observations and does not take into account the values in between. This means it can be affected by outliers and may not provide a comprehensive view of the overall variability in the data. As a result, other measures of dispersion, such as variance or standard deviation, may be more informative.
The median is least affected by an extreme outlier. Mean and standard deviation ARE affected by extreme outliers.
extreme lack of attention to medical care
Three standard deviations refer to a statistical measure that indicates the range within which approximately 99.7% of data points in a normal distribution fall. In other words, if you have a dataset with a mean (average) value and a standard deviation, three standard deviations above and below the mean encompass nearly all the data points, highlighting the spread and variability of the data. This concept is often used in quality control and statistics to identify outliers or extreme values.
The reason the standard deviation of a distribution of means is smaller than the standard deviation of the population from which it was derived is actually quite logical. Keep in mind that standard deviation is the square root of variance. Variance is quite simply an expression of the variation among values in the population. Each of the means within the distribution of means is comprised of a sample of values taken randomly from the population. While it is possible for a random sample of multiple values to have come from one extreme or the other of the population distribution, it is unlikely. Generally, each sample will consist of some values on the lower end of the distribution, some from the higher end, and most from near the middle. In most cases, the values (both extremes and middle values) within each sample will balance out and average out to somewhere toward the middle of the population distribution. So the mean of each sample is likely to be close to the mean of the population and unlikely to be extreme in either direction. Because the majority of the means in a distribution of means will fall closer to the population mean than many of the individual values in the population, there is less variation among the distribution of means than among individual values in the population from which it was derived. Because there is less variation, the variance is lower, and thus, the square root of the variance - the standard deviation of the distribution of means - is less than the standard deviation of the population from which it was derived.
The project sponsored by the United Nations to eliminate extreme poverty worldwide is called the Millenium Project.
In regards to Dell Computing it stands for eXtreme Performance System.
Directional selection
It would mean that the result was 2 standard deviations above the mean. Depending on the distribution of the variable, it may be possible to attach a probability to this, or more extreme, observations.It would mean that the result was 2 standard deviations above the mean. Depending on the distribution of the variable, it may be possible to attach a probability to this, or more extreme, observations.It would mean that the result was 2 standard deviations above the mean. Depending on the distribution of the variable, it may be possible to attach a probability to this, or more extreme, observations.It would mean that the result was 2 standard deviations above the mean. Depending on the distribution of the variable, it may be possible to attach a probability to this, or more extreme, observations.
The mean deviation is a measure of dispersion that calculates the average absolute difference between each data point and the mean. One advantage of mean deviation is that it considers every data point in the calculation, providing a more balanced representation of the data spread. However, a disadvantage is that it can be sensitive to outliers, as it does not square the differences like the variance does in standard deviation, making it less robust in the presence of extreme values.
Because the standard deviation is based on the square root of the sum of the squares of the deviations, and, as a result, the sum of the squares of the deviations puts more weight in outliers than does a simple arithmetic mean.Note: I wrote this and then had second thoughts, but I'm keeping it in so that someone with more knowledge can weigh in (pun intended). I'm not certain how the arithmetic mean factors into the question. I think the questioner, and definitely this answerer, is confused.
Directional selection tends to eliminate individuals at one extreme of a trait spectrum, favoring those at the opposite extreme. Over time, this can lead to a shift in the average value of the trait within a population.
When you are looking for a simple measure of the spread of the data, but one which is protected from the effects of extreme values (outliers).