Search results

  1. Miner

    What are options in R for time-series forecasting and deriving a probability distribution?

    I would not consider this as a time series problem. You seem to be describing a reliability problem instead. Unfortunately, the data does not fit any of the typical reliability distributions, forcing a nonparametric Kaplan-Meier analysis (below), which cannot be used to predict beyond the...
  2. Miner

    What are you listening to RIGHT NOW

    My tinnitus, unfortunately.
  3. Miner

    Simple Stats for Pre vs Post Sample Comparison

    Pre/Post test would typically indicate the use of a Paired t-test. However, you stated that the data cannot be matched and the sample sizes are unequal. This forces you to use the 2-sample t-test. You also want to know whether the post test is higher than the pre-test, so this dictates a...
  4. Miner

    Simple Stats for Pre vs Post Sample Comparison

    Since this appears to be homework, I will provide clues to guide you. Hypothesis tests are usually classified as: 1-sample or 2-sample. How many samples (groups, not n) do you have? If they are 2-samples, they can be paired or unpaired. Is your data paired or unpaired? Next, is your...
  5. Miner

    Dr Taylor Transformation for non normal data ???

    I am only familiar with the Box-Cox transformation (which includes all the standard Log, reciprocal, square root, etc. transforms) and the Johnson transformation. I have not heard of a Taylor transformation. Could it be associated with this person? He does not have a specific transform, but...
  6. Miner

    Comparing Two Sets of Data, Slightly Different Measurement Times

    Yes to both questions.
  7. Miner

    Comparing Two Sets of Data, Slightly Different Measurement Times

    The correlation is impacted by two things: Pearson correlation is for LINEAR correlations. This is not linear, so you should try a Spearman correlation. Or did you intend R^2 instead of correlation? They are not the same. There is a lot of scatter about the line. This could be caused by...
  8. Miner

    Comparing Two Sets of Data, Slightly Different Measurement Times

    Are there specific line items in which you are interested? P-values 1-tailed vs. 2-tailed tests.
  9. Miner

    Comparing Two Sets of Data, Slightly Different Measurement Times

    That would work okay for the paired t-test. If you want to see how the difference varies by temperature using regression, you would need the full data set.
  10. Miner

    Comparing Two Sets of Data, Slightly Different Measurement Times

    I think your idea for interpolation is reasonable. You can use a paired t-test to quantify the difference. You mentioned it in your original post, and I see in the graph that this delta appears larger on the peaks than it appears in the valleys. I would refrain from interpolating in the zones...
  11. Miner

    Comparing Two Sets of Data, Slightly Different Measurement Times

    I have one good idea, plus one not-so-good one. :D Start with plotting your data (good idea). The small sample you provided shows that there is a definite impact (at least during this time window). A question regarding the data validity. How large is your measurement variation? Is the...
  12. Miner

    Stationary and Mean Ergodic for random processes

    Not on this.
  13. Miner

    Help with correlation scenario

    I would think that only a very small percentage of people with a nosebleed actually go to an ER. Most would just put tissue in their nose until it stops. This non-response bias would be very large. How do you intend to deal with that?
  14. Miner

    How to linearly transform variables before t-test if their range is unknown

    This does seem more like a relationship between x1 and x2 rather than a difference. Plot the paired points with x1 on one axis and x2 on the other axis to see if there is a relationship. If there is, you can try a regression.
  15. Miner

    explaing basic stats concepts to my cat

    The dog would just agree with everything you said. How would you learn if the cat didn't challenge you?
  16. Miner

    explaing basic stats concepts to my cat

    The cat understands. It just does not care.
  17. Miner

    residuals linearity

    Do you have the ability to store your residuals then generate a plot similar to this where the color represents the density of the plotted points? Some call this a binned scatterplot. Or use a lighter shade of gray on your plotted points where it better shows the density of points?
  18. Miner

    residuals linearity

    It does not appear to show the indicators of nonlinearity. You want to focus on the most dense portion of the plot. Nonlinearity is usually pronounced. Of course you can always add a quadratic term and see what that does to your model (i.e., significance of term, AIC/BIC). It does not appear...
  19. Miner

    Using/converting KM survival data

    Focus on the "Years Since Intervention" and "Cumulative Failures" columns. Difference the "Cumulative Failures" column and match the differences with the correct "Years Since Intervention" rows. This will give you years matched with the number of patients that survived that long.