1. E

    Determine sample size to get a statistically significant result

    Hello, this question concerns the topic of A/B split-testing. More about it on wiki here. I need to determine what is sample size would I require to get a statistically significant result for my experiment. I can see how an economist at Google is doing it. However, our don't understand the...
  2. T


    I called 100 prospective clients at the beginning of the year; 30 said they may give me orders (type "O") and 70 said they would probably not give me orders (type "N"). Now, 6 months later, I see that I received orders from 20 of the 30 which said they may give me orders and I received orders...
  3. S

    What is the probability people are forecasting correctly with standard spreadsheets?

    It seems that many people are using standard spreadsheets to forecast, getting correlation coefficients, etc. However I decided I needed to write my own computer program so I could work out the likelyhood of the forecasting being correct. 1) If there is not sufficient correlation then...
  4. S

    Hypergeometric distribution appears to have hidden problems

    When I was writing a computer program to calculate hypergeometric distributions probabilities I had some funny results. This is because I just used the condition I found in a stats book. The book says: p(x) = formula with x =0;1;....;n where n is the size of the sample drawn and p(x) = 0...
  5. C

    Trying to calculate confidence intervals

    Hi everyone. The numbers below are the annual maintenance costs of a program I am working on. I'd like to use the data set to estimate future costs at different confidence intervals (e.g. 80%). Can you help me with what distribution would be best and how to produce a CDF that I can graph...
  6. N

    The probability of being born a male baby?

    Thank you! :)
  7. J

    Hypothesis testing

    test a claim that each can of soda contains exactly 11 oz. at the 3% level of significance, given that the mean volume of 10 cans of soda is 12.05oz with a known standard deviation of 0.06 oz reject or dont reject?
  8. P

    Probability Applications - Drawing from a Deck of Cards

    Hi! I am having trouble figuring out how to go about solving the following problem: "Find the probability of obtaining the given 5-card poker hand. - three of a kind" I have tried several different ways, most recently C(52,3) x C(13,4) x C(4,3) as well as C(4,3)/C(52,2)...
  9. M

    How to check if two categorical variables are related (in a two-way table)? Confused

    Hi, My question might seem pretty dumb but I'm teaching statistics to myself and never had in school or uni. I use a book and I'm currently trying to learn the chapter about two-way tables with two categorical variables. In the book, it is written that you can check if two categorical...
  10. I

    Probability of sample test

    I am struggling to understand this: first I have read the theory of discrete and continues random variable, and distributions. where an outcome is the random variable that behaves as a certain distribution. but I came across with a situation where I cannot compare it with the previous concept(...
  11. C

    probability plot analysis

    Hey guys. Would you say this probability plot shows normal distribution? I thought it did, because they all pretty much follow the line, or is that slight bit of difference enough to deem it not normal? Also when talking about the outlier of 4pin is that enough to deem it not normal...
  12. D

    Probability of relations in a network

    Imagine i have a predicate $friends(p_1, p_2)$ and I know that $p(friends(p_1, p_2)) = p_1$. If I generate a world of $n$ people, I expect there to be $\binom{n}{2}p_1$ friends. Now imagine I count the number of times that 3 people are all friends of each other in this world: $\binom{n}{3} p_3$...
  13. O

    dice rolling odds. please help!

    Suppose you have a FIVE sided dice. One of the sides has a star on it, the other four sides are blank. Suppose you rolled it 10 times. What are the odds that you would roll the star 4 out of the 10 times? can't figure this out, thank you so much!
  14. D

    Compound Probability

    Hey guys, i am having a bit of trouble with this basic probability question which shows that i do not understand the basics at all. The question is: What's the chance that a .250 hitter in baseball gets at least one hit in a game. (Assume the player has five at-bats) Firstly, I do not...
  15. M

    Just a guy from Sweden

    Hello fellow geniuses I live in Sweden and have been a Software Engineer for more than 10 years now. I am starting to learn about statistics and probabilities to hopefully change jobs in the next few years as I am fed up with software engineering since its very slippery slope and changes all...
  16. T

    weighting of aligned subsequences by their length

    I have a pool of subsequences, each one associated with a probability (and other properties that you don't need to know) that quantifies how frequently that subsequence occurs. In order to select those subsequences that may be part of a longer sequence (template sequence), I align them to the...
  17. M

    Risk Management

    There is 3% coral coverage in a sea area of l=200m b=5m. The size(diameter) of each coral is 50 cm. If we throw a block of 1m2 in the area. How many coral will get hit by the block?(probability I dont even know where to start. Even a small hint will be really appreciated. Thanks!
  18. R

    Help with a Poisson Regression Equation

    I have attached an image of an equation of Poisson Regression that i am working on for my data analysis project. I want to understand it a bit as i am new to stats. can anyone tell me whats that Capital 'T' symbol in power of w1 and w2 means? And can anyone guide me to coding this equation in...
  19. R

    Help with a Poisson Regression Equation

    I have attached an image of an equation of Poisson Regression that i am working on. I want to understand it a bit as i am new to stats. can anyone tell me whats that Capital 'T' symbol in power of w1 and w2 means? And can anyone guide me to coding this equation in Matlab? Thanks in advance...
  20. K

    Rolling a die 600 times

    So I was given a question that states that "A gambler buys a new die and throws it 600 times. Assuming the die is unbiased, estimate the probability that he obtains between 90 and 100 "sixes". What might he conclude if he were to have obtained 120 "sixes"?" A few people in my class suggested...