Recent content by spunky

  1. spunky

    random experimental data with prespecified odds ratio and CI

    It's pretty much impossible without coding. To do what you want to do, you will need to learn how to simulate.
  2. spunky

    Mediation Analysis

    Hi! We are glad that you posted here! This looks like a homework question though. Our homework help policy can be found here. We mainly just want to see what you have tried so far and that you have put some effort into the problem. I would also suggest checking out this thread for some...
  3. spunky

    checking whether I wrote a formula correctly in R

    I guess I gravitated towards that part of the equation because you're mentioning "weird results" and I'm thinking "OK, if the results are "weird" the only modification from the formula where I could see this coming from is that 100 part, because (at least when comparing what you did to what's...
  4. spunky

    checking whether I wrote a formula correctly in R

    Have you tried starting with the formula as originally intended, see if it make sense, then add the 3.6 factor part, see if that makes sense and finally the abs(x[adj])*100? Btw, the abs(x[adj])*100 seems peculiar to me. If something's weird I'd be willing to say that's where it is.
  5. spunky

    Normality: DV itself or residuals?

    But 'linearity' is not a parametric assumption. The issue that you bring forward (linearity) is an issue of model misspecification. Regression coefficients preserve their small sample properties even in the absence of normally-distributed errors because of the Gauss-Markov theorem
  6. spunky

    Normality: DV itself or residuals?

    This is very good advice. I remembered our (online) conversation yesterday when I was sitting on a 4th year undergrad course in econometrics. They were talking about instrumental variable (IV) estimators and deriving one of the 'simplest' forms of the standard error for this type of regression...
  7. spunky

    Normality: DV itself or residuals?

    Which is why I always advocate for collaborative work. For example, I am not a social psychologist. I wouldn't even dream of trying to set up a study on my own running it to get a publication. If I'm interested in something, I'd perhaps knock on a few people's doors and see if I can get involved...
  8. spunky

    Normality: DV itself or residuals?

    Uhm… I’m not sure if I’d be the right person to ask this because I’m very suspicious of rules of thumb. If you look into the theory where rules of thumb come from, you can almost always come up with enough counter-examples that either (a) make the rule of thumb invalid or (b) make it valid in...
  9. spunky

    Normality: DV itself or residuals?

    Social-science-land (including Psych, obviously) is in a very weird position these days. On the one hand, they all recognize (or pretend to recognize) the importance of statistical and methodological expertise. But, on the other hand, they prefer not to hire people with this kind of expertise...
  10. spunky

    Normality: DV itself or residuals?

    Yes, distributional assumptions are on the residuals of our models. I'm.... not sure what he means here. I mean, the sampling distribution of the standard deviation (coming from a normal parent population) is not normal. It is chi-squared. Maybe he means the sampling distribution of the mean...
  11. spunky

    Normality: DV itself or residuals?

    That in social science land it gets sold like the be-all-end-all of what a 'large' sample size should be. So I review article after article, paper after paper saying some variant of "all assumptions were met because n>30 and therefore the Central Limit Theorem applies (CITATION FORM A METHODS...
  12. spunky

    Normality: DV itself or residuals?

    OMG did the Andy Field book say that? And here was me hoping at least *he* would get things right. But unfortunately by the time this content moves from statistics to social sciences it has been digested and re-interpreted so many times that what you end up with is some bastardized version of...
  13. spunky

    Normality: DV itself or residuals?

    This is quite true indeed. I also come from a closely-related field (Education) and the quality of statistical/methodological training is abysmal and mostly at fault of people who do not quite understand these methods being tasked to teach them to the new generations. Every time I have student...
  14. spunky

    Answer to @Dason's question

    Dason asked yesterday: "Dason: Like how would you propose something simpler... like turning the equation for a circle into a pdf: x^2 + y^2 = 1" And because I'm in a procrastinating mood (I've got like a bazillion things to do before the end of the month) I thought about it during the evening...
  15. spunky

    How to remove negative values from a bell curve?

    The half-normal distribution, perhaps?