random

  1. W

    Fixed vs. Random Effects

    I'm wondering if someone could help me to correctly identify whether certain variables should be considered fixed or random effects. Just as context, I have a dataset of people (with information about them that I know is FIXED). I have a variable indicating to which healthcare practice...
  2. L

    Probability with Permutations Question

    Hello! This is my first time posting and I would appreciate any help at all! So the problem I'm working on has to do with randomly choosing letters from the alphabet and the probabilities that they make out words. The problem reads as follows: With your eyes closed, you are randomly...
  3. E

    Normal distribution

    Hi all, I'm generating a random normal distribution and i don't control the mu and sigma (its a matlab function that i need to use because the ratio between the numbers). Is there any way to change the mu and sigma and still keep the same ratio between the numbers in the vector? I hope you...
  4. D

    Manufacturing machine probability problem

    There are three possible environment conditions: normal, rainy and hot. Rainy and hot days may be risky to a system that has been deployed, but normal days are safe. It is expected that half of the days will have normal weather, one quarter will be rainy and one quarter will be very hot...
  5. D

    Generating random data from correlations

    Say I have a list of personality traits: courage, materialism, compassion and so on. I interview some people and assign a rating from -10 to +10 to each trait for each person, then I find the correlation between each pair of traits. Now I want to create a "random person" by assigning a value...
  6. J

    Binomial Random Variables

    Hey guys! I'm having some real trouble with these questions. Any help would be greatly appreciated! Thanks in advance (: 1.) A baseball player has a lifetime batting average of 0.183. If, in a season, this player has 250 "at bats", what is the probability he gets 29 or more hits? Probability...
  7. T

    Probability on Roulette. Just curious!

    Hello all. Could you help me? I have been discussing the following topic with my work teammates; We were talking about statistics and probabilities under roulette. What they say is that given an amount of time (it could be high or short), if we take examples of something that happened on some...
  8. O

    Equal chance of random selection when halves of set are balanced?

    Design: For 18 trials numbers (either 0 or 1) are randomly selected, a random portion of the first 9 are 0 and the last 9 are set as the opposite number of 0s. Within the first and last 9 the 0 or 1s are randomly assorted. The numbers are described as being in 3 consecutive groups of 6 called...
  9. P

    Random survey for crowd-sourcing similarities

    Hi all I have a data set of around 5,000 items that I need to test how similar or dissimilar people see each item as being from each other. In theory, the items should be able to be grouped up into major and minor groupings, providing the basis for a dendrogram structure. To do this, I'm...
  10. U

    Random variables and probability distributions

    The question i need help to is below: Laboratory tests on a large shipment [several thousands] of radios revealed that 6.5% are defective. On arrival of the shipment at the local distributor, 30 of the radios were randomly selected for a promotion. (a) Define the random variable for...
  11. M

    Tricky problem about 9 houses

    Ace Home Inspectors inspect nine houses each business day. Because AHI has been keeping records for several years they know that the probability of all nine houses passing inspection in a single day is 70%, the probability of eight houses passing on a single day is 20%, of seven houses...
  12. D

    GLM with Random Factors

    Hi: Newbie to SPSS. Tons of stats and programming knowledge ... but helping a novice with their SPSS work. We're doing a GLM with a random factor. When I put a factor in (incorrectly) as fixed I get one less piece of output, and when I put the factor in (correctly) as random I'd like to...
  13. F

    What is the difference between a white noise process and a random process?

    Hi, What is the difference between a white noise process and a random process? Thank you
  14. F

    the difference between non-stationary data and random data?

    what are the the difference between non-stationary data and random data? If we detrend a stationary data and make it non-stationary what will happen, will it be random?
  15. S

    Simulation of unlikely events over random binary variables knowing their probability

    Hi, I have n binary variables all having the same probability p of flipping. Probability is low, so I wouldn't want to go through generating a random number for every one of them in order to flip their value. I know that the expected number of flips for the n variables is m = n*p. I could use...
  16. W

    Fixed effects vs. Random Effects

    Hi we had 5 investigators 1)hand out 100 surveys and 2)record a certain feature of each of the 100 subjects. That feature that they recorded is the outcome and may be subject to the differing biases of the investigators (eg., an investigator may be too strict all of the time in their...
  17. O

    How to guarantee a "full random" selection from a group?

    Hi all, I need to create a full random selection of 5% from a group (>1000000 elements). The only criteria is, that all elements should have the same probability to be selected. The selected 5% will be compared against the full base later on, but there are no predefined attributes/segments...
  18. N

    Probability on 2 random events combined

    event A and B are not related but : if A happens then the event C has a probability W of happening. if B happens then the event C has a probability Z of happening. if both conditions happen A and B, Is the probability of C happening the combination of probabilities, W*Z then? Thanks
  19. S

    Generating Random Sample

    I know that SAS can easily generate random samples for know distributions - normal, exponential, uniform. But how can I generate a random sample from a known probability distribution (that is not listed)? The probability distribution is rather simple: f(x) = 2x^-3 So, how can I generate a...
  20. A

    Wilcoxon signed-rank test - Can I use for this case?

    Hello guys, I'm trying test if the results of a measurement variable (obtained with observation) is significantly greater than a other (obtained with random process). For the observed, I have an algorithm that returns a number. For the random I use the Bernoulli process, that returns another...