1. L

    Standardization of a variable

    Hello, before making a linear regression, how can I know if I have to standardize a variable?
  2. A

    quick stats question(standard error), please help!

    Suppose after performing a random experiment, it comes out that exactly 3 out of 20 to 30 year old males are shorter than 5.5 feet. consider the proportion of people in the sample that are shorter than 5.5 feet. What is the standard error of this sample proportion?
  3. A

    Stats question..Please help!

    Need help with this question ASAP. It is very important. Fiona takes part in two different choice-reaction time tasks as part of her research participation requirements for her psychology degree. After the experiment, the researcher tells Fiona that her reaction time was 270 milliseconds for...
  4. K

    Standard normal distribution

    Can someone please help me answer this Q with workings so I learn? Using a survey in winter 2009, it was estimated only 1% of households have solar panels to generate electricity. Consider a random sample of 20 houses. a) What is the probability that none of them have solar panels to...
  5. D

    Standard Normal random variable problem: I have no idea on how to start...

    Assume X is a standard normal random and Y ~ N(0,9). What is the 97.5 percentile of p(X) and p(Y)?
  6. J

    Why does sample std dev underestimate population std dev?

    The subject line is too short for me to word out my question properly: Why does (square root of unbiased estimator for population variance) underestimate population standard deviation? Refering to this wikipedia page Unbiased estimation of standard deviation, it says that "it follows from...