Yes, a standard deviation can be less than one.
You need more than one number to calculate a standard deviation, so 9 does not have a standard deviation.
Sure it can. But in the survey business, the trick is to select your sample carefully so that they'll be equal, i.e. a sample that is accurately representative of the population.
Absolutely. In fact I would commonly expect it to be. If, for example, the sample mean for the length of a bolt was 5.5 cm, you would certainly hope the standard deviation was a lot less than 5.5 cm. or it would imply bolts with a negative length (not quite sure how you'd do that without breaching some alternate dimension - no pun intended.)
Standard deviation in statistics refers to how much deviation there is from the average or mean value. Sample deviation refers to the data that was collected from a smaller pool than the population.
False. The standard deviation of a set is the square root of the variance, so it is not always smaller; in fact, it is always less than or equal to the variance when the variance is positive. The standard deviation can be equal to the variance only when the variance is 1 (since the square root of 1 is 1).
In general, a mean can be greater or less than the standard deviation.
Yes, the mean deviation is typically less than or equal to the standard deviation for a given dataset. The mean deviation measures the average absolute deviations from the mean, while the standard deviation takes into account the squared deviations, which can amplify the effect of outliers. Consequently, the standard deviation is usually greater than or equal to the mean deviation, but they can be equal in certain cases, such as when all data points are identical.
Yes. If the variance is less than 1, the standard deviation will be greater that the variance. For example, if the variance is 0.5, the standard deviation is sqrt(0.5) or 0.707.
When you don't have the population standard deviation, but do have the sample standard deviation. The Z score will be better to do as long as it is possible to do it.
Standard deviation can be greater than the mean.
A negative Z-Score corresponds to a negative standard deviation, i.e. an observation that is less than the mean, when the standard deviation is normalized so that the standard deviation is zero when the mean is zero.
There is no reason for that to happen.
Yes. Standard deviation depends entirely upon the distribution; it is a measure of how spread out it is (ie how far from the mean "on average" the data is): the larger it is the more spread out it is, the smaller the less spread out. If every data point was the mean, the standard deviation would be zero!
You need more than one number to calculate a standard deviation, so 9 does not have a standard deviation.
Yes, it can have any non-negative value.
It does not indicate anything if the mean is greater than the standard deviation.
Anand Mehta said yes and this is correct. You will get a SD, for example, if all of the data points are less than one, or if the data points are very close together and there is not much spread in the data..