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  1. Miner

    Help with stats work

    I am not a STATA or SPSS user, but I found the following on STATA's website: https://www.stata.com/statalist/archive/2011-10/msg00882.html and the following on a STATA forum: https://www.statalist.org/forums/forum/general-stata-discussion/general/1308432-detrended-variable-in-a-panel-dataset
  2. Miner

    Which statistical test suits better for my datas ?

    Given that answer, I would be inclined to use the 2-way ANOVA as described above. The group effect would answer your specific question. While the 2-sample t-test would do the same, you would not be able to test the interaction term.
  3. Miner

    Which statistical test suits better for my datas ?

    Why do you have hundreds of measurements per subject? Was this to reduce measurement error on a single cellular structure? Are there hundreds of cellular structures per subject? Or was it done over time (as in a repeated measures design)? You could use a 2-way ANOVA with groups and subjects...
  4. Miner

    Help with stats work

    De-trending subtracts the linear trend component from the data making it easier to see a potential discontinuity or jump in the data. Cambridge expenditures: This is an Individual control chart used in industrial statistics. It tests whether a process that generates times series output is in...
  5. Miner

    Help with stats work

    Trying to do what you want on the entire data set will be problematic because of the variation between institutions. i would recommend that you analyze select institutions that represent small, medium and large institutions individually using time series analysis. You can de-trend the data and...
  6. Miner

    Predicted R square

    At those levels of R^2, I would question whether you are truly using the model to make a prediction, or whether you are simply trying to understand how each factor influences the response. Using it to make a prediction brings Andrew Gelman's weighing the mass of a feather analogy to mind.
  7. Miner

    Predicted R square

    See the following blog on this topic. This should help explain some of the differences. Regarding your final question, the answer is "It depends". It depends on how good your model needs to be able to predict accurately and precisely. In some cases a model with an R^2 pred in the 70% range...
  8. Miner

    What type of study is this?

    This would be observational, which means you are passively collecting data as it occurs. Experimental means you are actively changing variables then observing the effect of those changes.
  9. Miner

    RESOLVED but still open for discussion: When to transform and when to use non-parametric tests?

    Here are my two cents worth (note: my background is industrial statistics): You lose information when you transform data Non-normal data sets are often the result of mixtures or from an underlying process that changes over time. Trying to transform these is a mistake. The usual argument for...
  10. Miner

    Logistic regression vs. cox proportional hazards model-which model to choose?

    This lesson may be of help to you.
  11. Miner

    RESOLVED: (Thanks Miner!) Best test? Before and After Cattle Trial

    I use Minitab 18. No coding required, which reduces the chance for errors. However, R is free and Minitab is not.
  12. Miner

    RESOLVED: (Thanks Miner!) Best test? Before and After Cattle Trial

    This does show a difference. You may have an error in your code. I think this forum limits file types to graphics, text and zipped.
  13. Miner

    RESOLVED: (Thanks Miner!) Best test? Before and After Cattle Trial

    Unfortunately, my company blocks external file shares. Try zipping it first. If that doesn't work, try saving it as a txt file.
  14. Miner

    RESOLVED: (Thanks Miner!) Best test? Before and After Cattle Trial

    Can you attach the data in Excel?
  15. Miner

    RESOLVED: (Thanks Miner!) Best test? Before and After Cattle Trial

    The boxplots show a difference.
  16. Miner

    RESOLVED: (Thanks Miner!) Best test? Before and After Cattle Trial

    Use Mood's median for unequal variances provided the shapes are similar (e.g., skewed in the same direction). Regarding your last statement, I am okay with the first sentence about variances. However, I would not state the part about logarithmic transformation unless you have verified that it...
  17. Miner

    RESOLVED: (Thanks Miner!) Best test? Before and After Cattle Trial

    Yes, you can use the Mann-Whitney test.
  18. Miner

    RESOLVED: (Thanks Miner!) Best test? Before and After Cattle Trial

    I would use Levene's test.
  19. Miner

    RESOLVED: (Thanks Miner!) Best test? Before and After Cattle Trial

    To be thorough, I would test for equal variances, but they visually appear to be different, which would indicate using KW or Mood's. I would be concerned about the long tails acting like outliers, so I would probably go with Mood's median. You have a large sample size, so power shouldn't be an...