log transformation

  1. C

    How to report t-test, CIs, cohen's d etc of log-transformed data

    I am wondering what is best/normal practice for reporting the results of an independent t-test of log-transformed data? For context, I am comparing the value of household assets for children who are attending pre-primary school with children who are NOT attending pre-primary school in Uganda...
  2. H

    Log-transforming Only the Dependent Variable

    For the regression: ln(gestation) = 5.28 + 0.0104×Birthweight For the birthweight and gestation data, Minitab tells us that coefficient of birthweight(b1) = 0.01041. minitab output: and therefore: exp(b1)=exp(0.010410)=1.01 The result tells us that the predicted median gestation changes by...
  3. R

    log(0) should have a real value!!!

    Dear all, I’ve been stuck for quite some time with a problem that relates to use of log-scale with values that equal zero. My data comes from an experiment in which five different instruments (one of them using the reference method) take two measurements of a given sample’s signal...
  4. F

    Log transformation of means

    Hey! I'm working on a meta-analysis and I want to use the means for moderator analysis. So some journal articles report log transformed values of the mean. In order to be able to conduct the moderator analysis, I need to retransform the logs. Two questions here: 1) Sometimes studies do...
  5. B

    Finding predicted values with logged (ln) dependent variable.

    Hello all, I'm currently working on my first quantitative project. I am doing an OLS regression in SPSS. I had to take the natural log of my DV in order for it to pass assumptions, and I want to do predicted values. I understand that merely exponentiating the sum of the regression...
  6. D

    Error term in log-level models?

    I am running a decomposition of log wages for two time periods and want to explain the variance of the error term. My question is: If there is a wage growth trend, will this automatically increase the variance of my error term over time (keeping the explanatory power of other variables in the...
  7. J

    error propagation

    I have a point estimate of quantity 'A' and an associated standard error. If I calculate a new quantity (= ln-transformed 'A' multiplied by a constant), how is the standard error of the original quantity 'A' propagated? How do I calculate the standard error for this new, transformed value...
  8. J

    error propagation involving log-transformed values

    I have a question about error propagation and log-transformed data. I have a measured value of 'A' (=5.20) and an associated standard error (=0.29). I have a measured value of 'B' (=10.07) and an associated standard error (=0.65). I need to report the difference in log-transformed...
  9. B

    4PL Non-Linear Regression, Transforming observed y values

    Good Afternoon, I'm currently teaching my self how to fit response curves, and have run into some trouble. I currently need assistance on utilizing proper methodologies to "massage" the observed y values. Is it wise to log transform the y values, knowing that this changes the vertical...
  10. R

    Normalizing Skewed Data

    Hello, I'm a novice in stats, and I wanted to know how to normalize 'skewed' data. I work with SPSS and I went to transform>compute variable> and then I do a log transformation... However, when I run the normality tests, I am still getting a significance of .000 for both the K-S and...