In: Statistics and Probability
A set of data is normally distributed with a mean of 37 and a standard deviation of 1.5. If you randomly select a data point and it is 37.75, which of the following would describe that data point?
Solution:
We are given that: a set of data is normally distributed with a mean of 37 and a standard deviation of 1.5.
That is: Mean = and standard deviation =
A data point is randomly selected and it is 37.75
That is: x = 37.75
We have to describe this data point
Note that: a number is unusually high or unusually low if it is more than 2 standard deviation from the mean and we can say a number is statistically significant.
If it is less than 2 standard deviation from the mean value, then we say this number is not unusual and it is not statistically significant.
z score gives number of standard deviations from the mean value for any x value.
Thus we use z score formula to find number of standard deviations.
Thus x = 37.75 is 0.5 standard deviation from the mean value and it is within +/- 2 standard deviation from mean value.
Thus correct description of the data point is:
Not unusual (Not statistically significant)