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  1. ME/CFS Science Blog

    Trial Report Causal inference between physical activity and chronic diseases: insights from a two-sample Mendelian randomization study, 2024, Qiu et al

    Sounds interesting. The GWAS for CFS (code: ukb-b-8961) had 2076 cases of self-reported CFS and 460.857 controls. Vigorous physical activity (VPA) and moderate to vigorous physical (MPA) were self-reported but light (LPA) and average physical activity (APA) were based on accelerometer data...
  2. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    We haven't posted or discussed this yet, but I think most statisticians would use a mixed linear effects model for this. That way they can account for the repeated measures (day1-day2) of participants but still test for differences between group. I've tried this using the following model: model...
  3. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    I don't know for sure but I suspect that the measuring device automatically averages multiple values over a short period (for example 10 seconds) and that becomes the score.
  4. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    There seems to be a moderate effect size for VO2 at peak values (not VO2 at the anaerobic threshold) with ME/CFS patients having lower values than controls, 63% of the time. The associated p-value is 0.005 but the authors tested more than 20 outcomes, at both the maximal and the anaerobic...
  5. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    One other thing that I've been looking it is Winsorizing the data, meaning cutting of the data at a certain percentile and replacing the values outside the limit with the percentile at both sides of the data. Winsorizing - Wikipedia I tried different cutoffs at 1%, 2.5% and 5%. For the VO_max...
  6. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    It's similar to CLES I believe. While CLES is the number of wins (groupA > Group B) divided by the total number of possible comparisons, cliff d seems like the (wins - loses) divided by the total number of possible comparisons. I get the same values as you using this formula. I think that...
  7. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    If found one that I find quite intuitive: the Common Language Effect Size (CLES). If you were to randomly take a participant from the ME/CFS group and a random participant from the HC group, how often would the ME/CFS patients have a lower value? If this was random noice and no equal values...
  8. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    Small differences like: Cohen_d_difference: I got: -0.129, you got: 0.12646 P_Welch_Difference: I got:0.424, you got: 0.432 etc. Did you exclude those 10 from AT? Is that necessary? I'm not sure that not hitting peak affects their AT values. No sorry, typo, the second overview I posted was for...
  9. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    Apologies for the wrong p-values, not sure what went wrong there. Here's what I got for values at AT and with PI-026 excluded. The first row looks very similar to your results for Work at AT (although for some reason, some figures are a bit different). One thing that strikes me is that...
  10. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    Yes I think you make a good point. When expressed as a percentage, there are 4 ME/CFS patients (PI-029, PI-087, PI-114, and PI-166) that have extreme values: That make the distribution of percentage changes quite skewed: With these 4 included, I found a cohen_d of 0.008 and p_value of 0.93...
  11. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    I think we largely agree. The data does not suggest that there is no difference at all. It's not 100% random noise. I would summarise it as: the data suggests that there might be an effect. But the effect is quite small with poor separation between groups and no correlation with the Bell...
  12. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    True, my graph looked weird because I checked precision below a certain value if the value was negative but above the value if it was positive. If I don't do this then I get the convergence to the ratio of ME/CFS patients in the total sample that you mentioned:
  13. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    I tried to look at the precision level for different values for the VO2_percentage change. I had it switch around the 0 point (checked for smaller values in case of negative values and for bigger values when positive values were used). Here's the code I used df = df_max values = np.arange(-40...
  14. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    Thanks @forestglip. Your coding skills are impressive and very useful. I think your analysis confirms that there might be a small effect. On the other hand, your approach is also iteratively looking for the best threshold, trying different things and looking for a value with the clearest...
  15. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    Yes I think we mixed up the terms. You we're right about the sensitivity and specificity values, but your description (how many with lower values than -9.7% would be ME/CFS patients) refers to precision rather than specificity. Here's what I got for a threshold of -9.7, for example: Total...
  16. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    Thanks again for the impressive analysis @forestglip. I do not get the same results though. For example if I use the threshold of -9.7% for max VO2 values, I get 25 ME/CFS and 7 healthy controls so that ME/CFS patients make up 78% of the sample rather than 90%. Because of the large overlap...
  17. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    Anyway, this is a bit besides the point. I plan to write a blog post about this because what the data shows is a quite different than what the paper reports and focuses on. - I think the data show that there is no significant effect for any of the outcomes, whether you look at AT or max...
  18. ME/CFS Science Blog

    Cardiopulmonary and metabolic responses during a 2-day CPET in [ME/CFS]: translating reduced oxygen consumption [...], Keller et al, 2024

    I've now recalculated with the correct comparison of ME/CFS patients but it is still the same large difference: This calculation first takes the means, then expresses the change in means as a percentage (day2_MECFS.mean() - day1_MECFS.mean()) / day1_MECFS.mean() * 100 Result: 9.4% This one...
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