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What percentage of scores fall within -3 and plus 3 standard deviations around the mean in a normal distribution?
Wiki User
∙ 13y ago
99.7% of scores fall within -3 and plus 3 standard deviations around the mean in a normal distribution.
Wiki User
∙ 13y ago
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What does standard deviation describes?
Standard deviation describes the spread of a distribution around its mean.
What standard deviation tells us about a distribution?
It is a measure of the spread of the distribution: whether all the observations are clustered around a central measure or if they are spread out.
Why is the mean the standard partner of the standard deviation?
The mean and standard deviation often go together because they both describe different but complementary things about a distribution of data. The mean can tell you where the center of the distribution is and the standard deviation can tell you how much the data is spread around the mean.
What is the z score representing the 10th percentile of the standard normal distribution?
Right around -1.28
What is a standardized unit that tells how far away each measurement is from the mean?
Standard deviation is a measure of the spread of data around the mean. The standardized value or z-score, tells how many standard deviations the measurement is away from the mean, and in which direction.z score = (observation - mean) / standard deviationStandard deviation is the unit measurement. This tells what the value a decimal is.
What is chumlee's IQ?
My best estimate is around 1.5 standard deviations away from the norm.
What does standard deviation describes?
Standard deviation describes the spread of a distribution around its mean.
How many outliers can a data set have?
There is no agreed definition of an outlier and consequently, there is no simple answer to the question. The number of outliers will depend on the criterion used to identify them. If you have observations from a normal distribution, you should expect around 1 in 22 observations to be more than 2 standard deviations from the mean, and about 1 in 370 more than 3 sd away. You will have more outliers if the distribution is non-normal - particularly if it is skewed.
What standard deviation tells us about a distribution?
It is a measure of the spread of the distribution: whether all the observations are clustered around a central measure or if they are spread out.
Why is the mean the standard partner of the standard deviation?
The mean and standard deviation often go together because they both describe different but complementary things about a distribution of data. The mean can tell you where the center of the distribution is and the standard deviation can tell you how much the data is spread around the mean.
Why use the squarred version of the sum of deviations from the mean?
You cannot use deviations from the mean because (by definition) their sum is zero. Absolute deviations are one way of getting around that problem and they are used. Their main drawback is that they treat deviations linearly. That is to say, one large deviation is only twice as important as two deviations that are half as big. That model may be appropriate in some cases. But in many cases, big deviations are much more serious than that a squared (not squarred) version is more appropriate. Conveniently the squared version is also a feature of many parametric statistical distributions and so the distribution of the "sum of squares" is well studied and understood.
What is the standard tip pool percentage in California restaurants?
Around 15 to 20 Percent.
3 Give a brief note of the measures of central tendency together with their merits and Demerits Which is the best measure of central tendency and why?
ANS: Measures of central tendency will quantify the middle of the distribution. The measures in case of population are the parameters and in case of sample, the measures are statistics that are estimates of population parameters. The three most common ways of measuring the centre of distribution is the mean, mode and median.In case of population, the measures of dispersion are used to quantify the spread of the distribution. Range, interquartile range, mean absolute deviation and standard deviation are four measures to calculate the dispersion.The measures of central tendency and measures of dispersion summarise mass data in terms of its two important features.i. With respect to nature of data to cluster around a central valueii. With respect to their spread from their central valueArithmetic mean is defined as the sum of all values divided by number of values.Median of a set of values is the middle most value when the values are arranged in the ascending order of magnitude.Mode is the value which has the highest frequencyThe measures of variations are:i. Range (R)ii. Quartile Deviations ( Q.D)iii. Mean Deviations (M.D)iv. Standard Deviations (S.D)Coefficient of variation is a relative measure expressed in percentage and is defined as:CV in %=
What is the z score representing the 10th percentile of the standard normal distribution?
Right around -1.28
What does standard deviation provide when measuring the range of possible outcomes of a distribution?
It is a measure of the spread of the outcomes around the mean value.
Why is the sample deviation divided by n-1in business statistics?
The purpose in computing the sample standard deviation is to estimate the amount of spread in the population from which the samples are drawn. Ideally, therefore, we would compute deviations from the mean of all the items in the population, rather than the deviations from the sample mean. However the population mean is generally unknown, so the sample mean would be used in place. It is a mathematical fact that the deviations around the sample mean tend to be a bit smaller than the deviations around the population mean and by dividing by n-1 rather than n provide the exactly the right amount of correction.
What is the importance of the standard deviation?
It allows you to understand, or comprehend the average fluctuation to the average. example: the average height for adult men in the United States is about 70", with a standard deviation of around 3". This means that most men (about 68%, assuming a normal distribution) have a height within 3" of the mean (67"- 73"), one standard deviation, and almost all men (about 95%) have a height within 6" of the mean (64"-76"), two standard deviations. In summation standard deviation allows us to see the 'average' as a whole.
