Recent content by hlsmith

  1. hlsmith

    rating the accuracy of predictions

    More information is needed for sure, but you could look at plotted observed vs expected values to see where the teachers are performing better on the spectrum of scores. Then go back and tease out student characteristics to see if something is telling (subgroups). Though, you would want to make...
  2. hlsmith

    Hello all, I'm Girl

    Hello, I am an old member here, not a robot. Greetings!
  3. hlsmith

    check if X variable influences Y or Y influences X

    If you are trying to figure out which variable predicts the other, this is an impossible task to achieve using statistics.
  4. hlsmith

    a logarithm transform of a predictor fixed proportional hazards in Cox model - how can that be ??

    The term significant is fairly arbitrary - are you talking 0.04 to 0.06, which may not be a change of magnitude beyond just being trivial.
  5. hlsmith

    Seeking Basic Statistics Resources

    You have the right place, ask away. the central limit theorem is very important in stats.
  6. hlsmith

    can someone please explain how the answer is 0.54

    conditional probability
  7. hlsmith

    How to calculate degrees of freedom

    I believe most methods have their own unique calculation. Though, many approaches are just special cases of other approaches so they have similar calculations. It depends on the method, so yes there are multiple approaches for different statistical test.
  8. hlsmith

    Standard Multiple Regression

    Yeah, I am just asking you to write out the potential regression model. difficulties = trauma + etc.
  9. hlsmith

    "The balancing property is not satisfied"
  10. hlsmith

    Standard Multiple Regression

    Are there multiple dependent variables?
  11. hlsmith

    "The balancing property is not satisfied"

    Why are you matching and what is the exposure of interest? I ask because many dislike PS matching compared to PS weights, see research by Gary King as well as Peter Austin. Not a Stata user, but would imagine it is about differences between score values (e.g., distance, caliper, or something).
  12. hlsmith

    a logarithm transform of a predictor fixed proportional hazards in Cox model - how can that be ??

    Did you plot the IV for each outcome group to see the distributions.
  13. hlsmith

    Seeking advice on my capstone project

    I would use an exact logistic regression model. Your model will struggle given the rare outcome event and comparison of three groups (a v b, a v c, c v b, which requires you to change your alpha value to account for false discovery). You can also, for simplicity use the Fisher's exact test...
  14. hlsmith

    SAS logistic regression

    Regardless, it comes down to common sense as well. If you have a rare outcome and an imbalanced categorical predictor - how well do those few individuals nested in those groups generalize to the super population. Do they represent everyone?
  15. hlsmith

    Observations for logistic regression

    I believe, Frank Harrel Jr. list 10-20 observations in the less outcome group for each predictor in "Regression Modeling Strategies". But many things come into play. Common sense works most of the time. Ideally you have lots of data and split it. in the training set you build the model and then...