1. J

    Distributions and means - confidence interval question

    Hi folks, :wave: I think I did my research but I would like to be sure before continuing. My task is to find the mean price of a given item in a given country and I need to know how accurate my sample mean is vs. the actual population mean. Here is what I have. (My proposed, probably...
  2. F

    Sampling Distributions help

    Hi, I'm teaching myself stats but have no idea on how to solve these, any help would be appreciated. When a pizza restaurant’s delivery process is operating effectively, pizzas are delivered in an average of 45 minutes with a standard deviation of 6 minutes. Suppose each night, 9 deliveries...
  3. A

    Need help with Uniform probability distribution

    Hey guys... I'm sort of confused about these two problems. If you guys can help me out that would be great. Problem: Suppose X is a random variable best describe by a uniform probability distribution with c=3 and d=5 . Find the following probabilities. a) p(x<4) b) p(x>2) Thanks,
  4. K

    I really need help on my homework!

    Theres 2 questions I'm really stuck on. One has three parts and is of course one of those "you can't do the next step until you get the first step" kind of thing.\ 1.A set of reading scores for fourth-grade children has a mean of 25 and a standard deviation of 5. A set of scores for...
  5. 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...
  6. F

    classification of probability distributions

    Hi, I wonder if there is a classification of probability distributions or so called 'controlled vocabulary' or 'ontology'? So far I could find following classification patterns 1. Parametric a. continuous with a probability density function b. discrete with a probability mass function...
  7. G

    Test for symmetry? [Please]

    (This was posted in a different sub-section of the forum, but has remained unanswered for over a month. I'm posting it here in the hopes of getting a respondent.) I'm doing a psychophysical study on motion direction estimation and the direction-dependence of the estimation errors. My current...
  8. B

    cumulative distribution function problem

    I have this question I am trying to get through but i keep coming into trouble. The question is: Show that the cumulative distribution function from a uniform distribution of the random variable is Fx(y) = (y-a) / (b-a) for some a < y < b I've started the question but have become stuck...
  9. C

    Estimating parameters of simulated Normal Data sets

    Dear Sir/Madam, I am doing a simulation study. For my study, I need to simulate 10,000 data sets from standard normal distribution(each with 100 observations) and need to estimate the mean and standard deviation parameters of all 10,000 data sets. I used replicate function to generate...
  10. G

    Test for symmetry - comparing multiple pairs of distributions?

    Hi all, I'm doing a psychophysical study on motion direction estimation and the direction-dependence of the estimation errors. My current problem is determining whether the perceptual bias of a motion direction is symmetrical around a cardinal direction. So what I have are: multiple...
  11. B

    Combining Bernoulli distributions

    Combining Bernoulli distributions [Solved] I'm looking for a way to find the standard deviation of a certain distribution. This distribution is created by performing n_0 Bernoulli trials with probability p_0. The number of successes is recorded as n_1. n_1 Bernoulli trials are then performed...
  12. J

    Should you transform skewed data when the distribution is expected?

    Hi all, I have been discussing this topic all week with people in my department and I can't seem to get a straight answer. I also tried posting this thread in a non-psychology forum and received only a few straight of the textbook responses about positive skew. I was taught long ago that you...
  13. J

    Should you transform skewed data when the distribution is expected?

    Hi all, I have been discussing this topic all week with people in my department and I can't seem to get a straight answer. I was taught long ago that you should not necessarily transform a variable if the population distribution is expected to be skewed (for use in regression analysis). For...
  14. B

    predict what shift in mean bell curve will look like for empl rating data scale 1-5

    Right now I have the regression equation to predict the STI%bonus based on their Rating but I also want to see the how the dist. curve will look as it shifts to the right since max rating is 5 Here is the link to my excel file - post http://sdrv.ms/LtEdcR I am Really trying to...
  15. Quadrapolis

    Target Mrgn of Vic with % of votes remaining in election: Is this a Hypergeom. Dist.?

    Thank you a million for any help you might be able to provide. I've been plugging away at this on and off for a couple weeks now. I'm not well-versed in probability and statistics, but I learn as I go. I've attached a couple of Excel spreadsheets. The first is a spreadsheet I built to try to...
  16. T

    Parametrising LogNormal distribution knowing only sample mean, and 90th percentile

    I'm a little stuck, and hope someone will be able to explain this to me. I have sample mean, and value of the 90th percentile of the sample. If distribution is assumed to be LogNormal, is there a way of estimating parameters of mu and sigma of that LogNormal distribution? I'm trying to...
  17. C


    Distribute six energy units to four different states, 0ε, 1ε, 2ε, 3ε, with the constraint that the total energy of the system is equal to 4ε which must determine the weight and n(ε) for each energy level.
  18. X

    How to interpret the density of a uniform prior (graph)?

    The graphs are found in the link attached. They are on slides 10, 12, and 13 (although, 12 and 13 should be the same graph, one is just coloured). What do the axes represent? What is the graph telling us? http://www.maths.adelaide.edu.au/media/talks/The_two_envelope_problem.pdf
  19. I

    Binomial + Binomial

    Hi, I'm having difficulty working with the binomial - specifically aggregating binomial distributions. Hoping somebody can tell me where I'm going wrong. Let me give a totally fictional example: In a soccer match, there are 40 attempts at scoring a goal. Of these, 5 go in. Hence the...
  20. S

    Parametric or non-parametric for 2 sets of data being compared one normal one not

    Hi folks, I am in a dilemma and maybe one of you can help. I have 2 sets of data, one from a control group and one from an experiment group. Each group took a test before and after a period of time and difference calculated. When checking for normality within the data via Anderson-Darling I...