normal distribution

  1. P

    Sample size - chi-squared vs. normal

    Hi, I apologise if this is the wrong thread. I need to calculate sample sizes, but I'm curious as to why the commonly used Krejcie-Morgan tables use a chi-squared formula rather than a student-t or a normal distribution. I see quite a few other papers that use the latter distributions...
  2. L

    Finding IRQ from standard deviation and normal distribution

    Here's my problem. Any help or insight would be greatly appreciated: A report provided a standard deviation on waiting time to single room occupancy hotels to be 12.9 days. Given that the waiting times follow a Normal distribution, what is the IQR here (single number)? Thanks in advance!!
  3. P

    the third statistics independent with sample mean and variance

    As we know, if X1, X2 ... XN are IID normal distribution, then the mean of the samples and the variance of the samples are independent. My question is, could we use X1, X2 ... XN to construct the third statistics, which independent with the sample mean and variance.