skew

  1. Z

    The effects of transforming skewed data

    Hi There, I would like to know more about transforming data. I know that for parametric statistics data needs to be normally distributed, but I am confused about when this does and does not apply. Doesn't transforming data to make it normally distributed hide any experimental effects you...
  2. C

    Transforming Negatively Skewed Independent Groups

    I have two independent groups, (roughly 30 in each) – and their performance on 3 different tasks, there are 10 scores in total for each group. The majority of them are negatively skewed so I know I have to reflect the data before I transform it – if the two groups have different maximum...
  3. D

    Excel formula for the inverse Pearson IV distribution?

    Hello Everyone, What is the excel formula to generate the inverse Pearson IV distribution? I have mean, standard deviation, skew and kurtosis and I plan to generate random outputs given those stats. How do I write the formula? My question is very direct and simple. I've looked everywhere...
  4. G

    Conceptual Question: Experiment where you analyze different skew between conditions.

    Hi all, I had a psychology stats exam yesterday and one question was: 'Present a hypothetical experimental question in which the main interest is the difference in the skew of the dependent variable for different experimental conditions.' I understand this to mean that you have two or...
  5. C

    Normality tests and Shape statistics contradictory

    Hello. I am testing for normality on a number of repeated measures variables in a sample of 29 people. Both the Kolmogorov-Smirnov test and the Shapiro-Wilk test statistics say that all of these variables are significantly non-normal. However, observations of skew and kurtosis (as well as...
  6. J

    Should you transform skewed data when the distribution is expected?

    Hi all, I have been discussing this topic all week with people in my department and I can't seem to get a straight answer. I also tried posting this thread in a non-psychology forum and received only a few straight of the textbook responses about positive skew. I was taught long ago that you...
  7. J

    Should you transform skewed data when the distribution is expected?

    Hi all, I have been discussing this topic all week with people in my department and I can't seem to get a straight answer. I was taught long ago that you should not necessarily transform a variable if the population distribution is expected to be skewed (for use in regression analysis). For...
  8. K

    How much skew is too much?

    Hello, I am trying to do a linear regression, with a Response Time as my DV with R. When I run a gvlma with the model, the skewness always comes back as assumptions not satisfied. I checked the skewness of the DV and it came out as 0.26. Is this too much skew? I've tried log and sqrt but...
  9. R

    Transforming Variables

    I have several different variables. The majority of the variables were positively skewed and therefore I did a log10 transformation to make them more normal. However, two of the variables were quite normal already and now after log10 are more negatively skewed. In order for me to do some...