Recent content by obh

  1. O

    Regression Question Regarding Wins

    Hi Doublej, Did you try logistic regression? Usually, you don't use the regression to choose IVs. If you do you should choose a smaller significance level
  2. O

    comparing frequencies between time frames - best choice of analysis?

    Hi Bridieg, Do you want to compare the totals? or the distribution between the months? Not sure about SPSS, you may also use R If you want to compare only the total: > obs<-c(62,34) > prob<-c(0.5,0.5) > chisq.test(x=obs, y=NULL, correct = FALSE, p=prob) Chi-squared test for given...
  3. O

    t-test vs. Wilcoxon-test

    Hi Emre, The t-test and the Wilcoxon test doesn't check the same thing, so you don't expect to get the same result... 1. If you want to check if the probability to get a random value that is smaller than zero equal to the probability to get a random value that is larger than zero then choose...
  4. O

    solve part a and b .

    Please show how did you try to solve the question.
  5. O

    Help with this easy exercise

    Great, let me know what you got
  6. O

    Help with this easy exercise

    Hi Eco , as you state it is really easy ... did you manage? You just need to keep the full equation, set z into X and Y, and do basic algebra, then use the 2 formulas E(aX+b) and E(x^2). {Z instead of X in your case} You can't separate the equation (like you separated E(x-μx) ) as there is a...
  7. O

    Help with this easy exercise

    Typo I'm sure I wrote : E (aX+b) =aE(X)+b
  8. O

    Help with this easy exercise

    You need to set Z into X and Y, Also use the following formula: σ^2=e(x^2)-(e(x))^2
  9. O

    Help with this easy exercise

    E (aX+b) =aE(X)
  10. O

    Chow test in logistics regression

    Hi Traore, What is poverty_1, poverty_2? dummy variable of categorical variable with 3 values? What are the possible values of poverty? The only male regression and the only female regression have less power than both sexes regression. Generally, a sample size of more than 1000 should be big...
  11. O

    Chow test in logistics regression

    Hi Traore, If the theoretical model says it should be significant, and the full model with boys and girls is significant, so poverty is significant. I expect that with a larger sample size the partial models will also be significant... PS what are the p-values of poverty in each of the 3 models?
  12. O

    Sample size considerations

    Hi CC How do you plan to predict? What do you want to predict? Is the prediction change over time? What test do you want to run?
  13. O

    Chow test in logistics regression

    Hi, You didn't answer all my questions :), so I will try to have a general answer. 1. Statistical tests with a greater sample size (60) will have greater power to identify smaller effect sizes than tests with a smaller sample size (30). If you want to get better intuition you may do a simple...
  14. O

    How to find the right test

    Hi BP, So the DV is the donation sum, and IV is the stress level? Do you mean 80 options of organizations and the participant decide to donate to one organization? How many participants? Do you have any other IVs?
  15. O

    Chow test in logistics regression

    Hi Traore, What is the dependent variable (DV)? and what are the independent variables (IV)? If for example, you have 30 boys and 30 girls Do you mean that when you run logistic regression over 30 boys or over 30 girls the IV poverty is not significant? And when you run it over 60 children...