normal

  1. S

    Stats analysis struggling

    Hi, I am conducting an experiment where I am assesing 4 groups undergoing 2 treatments. 3 groups have recieved same treatment and 1 group has recieved the other treatment. I have averaged values of the 3 groups. It is a pre and post experiment. I want to compare the data for both pre groups...
  2. S

    Statistical Analysis using Minitab

    Hi, I am conducting an experiment where I am assesing 4 groups undergoing 2 treatments. 3 groups have recieved same treatment and 1 group has recieved the other treatment. I have averaged values of the 3 groups. It is a pre and post experiment. I want to compare the data for both pre groups...
  3. D

    Normal Distribution: MLE, UMVUE & MSE

    Attached is a problem regarding MLE and UMVUE of a normal sample. Does anyone know how to do b) the MSE part? The use of An is confusing.
  4. D

    Cope with distributions that may take negative numbers

    Hi to everyone, I would like to know how to cope with distributions that may take negative numbers when it is physically impossible. For instance, the lifetime distribution of an equipment, which obviously cannot be negative, but sometimes could give negative numbers. What can I do to avoid...
  5. V

    Sample Distribution Probability (unsure if correct answer)

    1. Carlinville, Illinois, has just started an ambitious recycling program. Special trucks collect recyclable products once a week, sorted into barrels of paper, glass, and plastic. The amount of glass recycled per week by a single household is normally distributed with mean 27 pounds and...
  6. P

    Density probability of a normal distribution at a point in a CASIO calculator

    I do not understand the utility of calculating the density probability in a point in the case of a continuous variable (for example in the case of the normal distribution). Some CASIO calculator include a function ("normal P. D.") which calculate the value of the density function of normal at a...
  7. I

    Normal Approximation to the binomial

    I'm trying to calculate the probability that there are greater than 300 successes from a pool of 1000 trials. I am told to use the normal approximation to the binomial and this is where is gets confusing. I have tried calculating the standard dev using =SQRT((100*0.3)*(1-0.3)). I am on the right...
  8. hanialbarni

    How to test data if it is normal distribution in spss ?

    Hello Good morning guys i will need some help truly i have variables in spss most of them scale type, some of them are nominal, and few are ordinal. My questions how can i get the graph for normal distribution for the whole data ? shall i combine all scales into one variable and combine all...
  9. C

    Need help starting this question; unable to identify what type of question it is

    I can't tell if its asking for a binomial distribution or a normal probability distribution.. or maybe an approximation of a binomial distribution using a normal distribution..but then where does a random variable come in? here is the question: A company that manufactures mufflers for cars...
  10. E

    What type of distribution is?

    Usually results of direct measurements are normally distrubuted. Also, if we make linear transformation on result. e.g. if X it is a normally distrubuted random variable, also Y=a+bX also it is. Statement is not any more thrue, if we make exponential or logaritmic transformations. e.g. if Y...
  11. K

    What type of distribution is this and am I being sensible?

    I have a computer model, which I need to run 3500 times with different input parameters. The model's accuracy depends on a constant, let's call it T, which unlike the input parameters doesn't change between model runs. By decreasing T, the model's accuracy improves but the computational cost...
  12. F

    How to calculate conditional density

    Hi, If we have a bivariate Gaussian dist as N(m, a). m=mean and a=variance. how can we find f(x|y) in terms of m and a? Thanks
  13. D

    Distribution of Extreme Spread for (n, sigma)

    Given a Rayleigh process R(s) generating samples X_i -- which is equivalent to a bivariate normal process with 0 correlation and both sigmas = s -- what is the distribution of the Extreme Spread of n samples? Extreme spread ES\{X\}_n \equiv max_{i, j}|X_i - X_j| E[ES_n(\sigma)], and...
  14. V

    Confidence Intervals affected by type of distribution

    How is the accuracy of confidence intervals affected by the population of interests distribution? I'm having some trouble wrapping my head around this. Thanks!
  15. C

    Test for error of central tendency

    Dear community, I have two groups of users who rate on 7-point-scores for n data items. Now I want to test whether there is a difference in both groups in their error of central tendency, i.e.: does one group tend to rate more towards the middle of the scale than another? I assume the...
  16. C

    Best test for normal distribution with as little samples / highest accuracy

    Hi there, I only completed one statistics class yet and now struggle with my first project involving statistics. :-) I want to conduct an evaluation where items are rated according to particular scales, leading to a lot of probability distributions, where there is one distribution for each...
  17. S

    Is normal dist OK for these count data?

    Hello, I am modelling some count data (ANCOVA). I use R for statistical computing. I am not sure if I must use a glm with poisson errors. There are 120 counts in 4 groups and only one zero count. The maximum count is 12. The median is about 4 and the distribution of...
  18. A

    Probability on a normal curve

    Hey all - It's been a long time since I was in school looking at probability and statistics. i have a bit of a difficult question for me. I have two sets of data: Data Set A has a Mean of 7.9 and a standard deviation of 0.79. The other set of Data, Set B, has a mean of 10.1 and a STD Dev of...
  19. K

    Updating covariance matrix when more info becomes available.

    Say, I have a solution to a 3D problem in the form of a a triple (x0,y0,z0) with uncertainty specified by an error covariance matrix S. Using these one can calculate and plot say the 1 sigma ellipsoid around this solution. Now suppose someone tells me that my solution "z=z0" is in fact...
  20. B

    Deriving Var from mu and two Ps

    If I know the mean of a normal distribution and two probabilities F1=P(Z>z1) and F2=P(Z>z2), I should be able to derive the Var of the distribution, no? Can't figure how. Do I need to manipulate the CDF algebraically, or is there an easier (non-calculus intensive) way? In real terms, I know...