Find the standard deviation for the following group of data items.
\[
9,11,11,16
\]

Step 1 ：Given the data set \(9, 11, 11, 16\)

Step 2 ：Calculate the mean of the data set: \(\frac{9+11+11+16}{4} = 11.75\)

Step 3 ：Subtract the mean from each data point and square the result: \((9-11.75)^2, (11-11.75)^2, (11-11.75)^2, (16-11.75)^2\) which gives \(7.5625, 0.5625, 0.5625, 18.0625\)

Step 4 ：Calculate the mean of these squared differences: \(\frac{7.5625+0.5625+0.5625+18.0625}{4} = 6.6875\)

Step 5 ：Take the square root of the mean squared difference to get the standard deviation: \(\sqrt{6.6875} = 2.586\)

Step 6 ：Final Answer: The standard deviation for the given group of data items is \(\boxed{2.586}\)