sample mean

  1. P

    Sufficient sample size

    I'm very new to the world of statistics. Could someone explain to me in layman's terms the following: I have complete data on a population size of ~37,000. I can show, across the entire population, that there are trends between certain variables and the amount of debt (e.g. age, length of tenure...
  2. H

    Confusing question on z-score for sample mean

    Hey folks, I was hoping someone would understand this better than I do. I am trying to solve the following problem: We are testing the hypothesis that the average gas consumption per day in Billings, Montana is greater than 7 gallons per day; we want 95% confidence. We sample 30 drivers. The...
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    MGF of sample mean of IID poisson RVs

    I am given the MGF of IID RVs as e^{\lambda(e^t-1)} and am supposed to find the MGF of their sample mean of n such RVs. I have am arriving at M_n(t) = e^{n\lambda(e^t - 1)+1} This doesn't appear to be a valid MGF and there is another part to the question where it asks for the \lim_{n...
  4. P

    Deducing Sample Size from Sample Proportion CI

    How do I approach this problem? Suppose we want to estimate a sample proportion to within 0.05 with 95% confidence, how large will the sample have to be? There is no other information about the distributions of the population or the sample. No point in trying to solve for n in the...
  5. H

    Comparing 2 means (binomial distribution type) between 2 groups

    Hi, I feel stupid for asking this, but I have a basic "why" question about obtaining the mean values to later run a 2-sample t-test to see if 2 groups are significantly different. I've read online that for binomial distributions (ie yes/no answers, successes/failures, etc) the mean = np, where n...
  6. E

    help! sample mean problem!

    Hey, just looking for some help on this problem, haven't done statistics for a while and don't know what I'm doing! Thankyou!! :)
  7. S

    Comparing two means

    Comparing two means Hi. I have some trouble comparing two means in SPSS. I am writing a thesis about audit exemption in Norway, and have found 48 000 companies in the population. 11 000 of these are registrated with e - mail, and are used in my sample. To defend this sample I have to...
  8. S

    Comparing two means

    Hi. I have some trouble comparing two means in SPSS. I am writing a thesis about audit exemption in Norway, and have found 48 000 companies in the population. 11 000 of these are registrated with e - mail, and are used in my sample. To defend this sample I have to compare the mean of...
  9. S

    Uniform distribution question

    Large random samples of size n are taken from a population which follows a uniform distribution with mean 25 and variance of 22. a) What is the expected value of the sample mean? b) Can the Central Limit Theorem be applied in this case? c) The probability that a sample mean is greater than 27...