Which of the following is true about the sample standard deviation (as opposed to the sample estimate of the population SD)?
1) It is a biased estimate of the population SD; it overestimates the population SD
2) It is an unbiased estimate of the population SD; it underestimates the population SD
3) It is an unbiased estimate of the population SD; it overestimates the population SD
4) It is a biased estimate of the population SD; it underestimates the population SD