sampling distribution

  1. G

    Construct a 95% confidence interval for the population proportion of all students...

    A researcher wants to know what proportion of all students who have completed a course in Statistics do not have a solid understanding of what a Sampling Distribution is. A random sample of 320 students who recently completed a Statistics course were given a basic exam on Sampling Distributions...
  2. L

    Shape of Sampling Distribution

    What will happen to the shape of the sampling distribution of sample mean as the sample size of a random sample increases? Shape-wise. Thanks so much.
  3. R

    Sampling Behavior of a count

    Undercoverage is a problem that occurs in surveys when some groups in the population are underrepresented in the sampling frame used to select the sample. We can check for undercoverage by comparing the sample with known facts about the population. a) Suppose we take an SRS of n= 500 people...
  4. G

    sampling distribution question help.

    "Mendel’s laws of inheritance indicate that individuals in a second-generation cross have a 75% chance of carrying a dominant trait and a 25% chance of carrying a recessive trait. Inheritance occurs independently in each individual. What is the sampling distribution of the proportion of...
  5. V

    Help Reviewing Central Limit Theorem Multiple Choice Questions

    Hi All, Can someone help me review my answers below? This is a practice quiz and I am unable to get a good score. I am not sure which question I am getting wrong. My answers are highlighted in bold. :shakehead Question 2 An insurance company has 150,000 automobile policyholders. The...
  6. C

    Probability and Sampling distribution

    Would you please explain me the difference between *Probability distribution and Sampling distribution* easily ? Is that the difference : in probability distribution we have probability for every individual whereas in sampling distribution we get probability for statistic ? Does sampling...
  7. T

    Sampling distribution for dissimilarity index

    The dissimilarity index is a well known metric used to measure spatial unevenness between two groups. Does anyone know of a sampling distribution that has been found for this particular statistic?
  8. J

    An Exercise of noncentral [math]\chi^2[\math] distribution.

    An Exercise of noncentral chi-square distribution. Let Y_1,\ldots,Y_n be independent random variables with Y_k distributed as N\sim(a_k,\sigma^2) , and \bar Y=\sum_{k=1}^{n}\frac{Y_k}{n} denote the sample mean, S^2 denotes the sample variance. Then show that...
  9. I

    Help with small-sample sampling distributions

    Hello, I'm having problems to build an approximate distribution for the mean and the standard devistion using a results from a sampling distribution with number of samples=10. Should I use t-student distribution for the mean and chi-square for the standard deviation? Please I would appreciate a...
  10. D

    Standard Error - interpretation and relative standard error

    Hi, I am unclear about how to interpret the Standard Error of the Mean (SEM) directly. For example, when a mean is reported as 5.00 + 0.50SEM, how do you directly relate the 0.50 to 5.00? To help address this question I have written dot points about what I know about the SEM and interspersed...
  11. C

    Bootstrap bias

    Good day forum, I'm using a bootstrap approach to get a better understanding of a sampling distribution. I've heard that the bootstrap approach introduces a specific bias into the results. Would anyone be so kind as to explain this to me, and how to compensate for this - or otherwise refer me...
  12. M

    Confusing Sampling Distribution Problem

    Ok, I was understanding how to work sampling distribution problems until I came to this one, and I cannot figure out how to do it for the life of me: Let X be the lifetime of an electronic device. It is known that the average lifetime of the device is 717 days and the standard deviation is 90...
  13. A

    Sampling distribution

    Hi, I have to calculate mean and standard deviation of sample means of size 30 (with replacement) from a population of size 87. Its impossible to do it without the help of any software because N^n is 87^30. I tried to get this distribution by using SPSS but it only generates random...
  14. M

    sampling - distribution of sample mean

    How do I solve this? I'm a little confused by the question itself too. A student's performance is equally good in both subjects. The marks she might be expected to score in each subject may be treated as independent observation drawn from a normal distribution with a mean of 45 and standard...
  15. G

    [Matlab] - Stratified Sampling of Multidimentional Data

    I want to divide a corpus into training & testing sets in a stratified fashion. The observation data points are arranged in a Matrix A as A=[16,3,0;12,6,4;19,2,1;.........;17,0,2;13,3,2] Each column of the matrix represent a distinct feature. In Matlab, the cvpartition(A,'holdout',p)...
  16. J

    confusion on terminology

    I could use some confirmation or correction on something basic that has been confusing me for a while. It has to do with "normal" and steps in modeling. Normality is for residuals (people already helped me with this in a previous thread) and this comes after fitting a model. In the beginning of...
  17. A

    Differentiating between different distributions

    In my last 3 statistics classes I have learned about several different kinds of distributions: the binomial probability distribution the normal probability distribution sampling distributions I am findng it difficult absorbing all this information regarding distributions at once and...
  18. K

    Sampling distribution, Type II errors, and one-tailed tests

    For the past year, I have spent about 4.00$ a day for lunch, give or take a quarter or so. (a) draw a rough sketch of this distribution of daily expenditures (b) if, without looking at the bill, I paid for my lunch with a 5$ bill and recieved 0.75$ in change, should I worry that i was...