Markov cohort simulation in R - Our first probabilistic sensitivity analysis
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- เผยแพร่เมื่อ 21 ก.ย. 2024
- We previously ( • Markov cohort simulati... ) wrapped our model in a function so that we would be able to do sensitivity analyses. Now we see how that gets done in practice with a probabilistic sensitivity analysis (PSA).
Code for this lesson is available at gist.github.co...
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Dear Tristan, after a long time just came across this one! super helpful and efficient. Brilliant as always. Thanks!
Great to hear from you Hesam 😊
Thanks for sharing..
Thanks for watching!
Thank you so much. Really appreciate it.
You're very welcome!
Thank you very much for your videos. These videos are very helpful. It would be a great if you have a video of deterministic sensitivity analysis in Rstudio.
Thank you! I have that on my list of things to cover when I get around to doing more videos. You may find this thread I put together useful: twitter.com/TMSnowsill/status/1696845427646341285
Any new videos with the new bacon version in R? I am not sure which ages to use from the results txt file bacon produces as a result
Any help would greatly be apprecited!
Is this basically a Monte Carlo simulation? Or is this different? You could get the mean and 5th and 95th percentile from the results at the end as the CI95?
Yes, it is an example of Monte Carlo simulation. You can use the percentiles to produce credible intervals for the different outcomes. If you want to produce a credible interval for the incremental cost-effectiveness ratio (I don't necessarily suggest you do) the commonly accepted method is to read off the cost-effectiveness acceptability curve at 2.5% and 97.5%, but it is best to interpret carefully.
So many thanks for your great efforts and these videos are really helpful to me! Actually I am doing my assignment by following your videos. Is there any chance to learn that how to draw the plot in excel?
Thank you for making and sharing this series of videos I found they are very helpful. I am not sure if it is possible to you to make videos teaching how to compare intervention vs no intervention.
Hi there! I will absolutely be doing videos of comparative analyses in the future, they are fundamental. Unfortunately work commitments have stopped me from making videos for longer than I anticipated.
Thank you for your providing this video. These videos are very supportive and I am really appreciating. However, I could not understand well how to set the parameter for beta or gamma distribution even after I watched the you tube video regarding the gamma distribution and beta distribution. I am a bit confused with the video of beta or gamma distribution. I am happy if I know more detail or other example or etc about how to set the parameter for each distribution. Are there some specific number to use for Markov model analysis, for each parameter, rgamma(N_psa, Shape=○, ○/○) rbeta(N_psa,○○) in ○part? Or every time should we decide what number we put?
Hi there, sometimes we will determine the parameters for the distributions using the method of moments. In this case we specify, for example, the mean and variance we want the distribution to have, and we then calculate the parameters which produce that mean and variance. See for example en.wikipedia.org/wiki/Beta_distribution#Method_of_moments for the Beta distribution. For the gamma distribution, if we use the shape (k) and scale (θ) parameterisation, then the expected value (mean) is kθ and the variance is kθ². Therefore we can set θ = variance / mean and k = θ / mean (or k = mean² / variance).
For gamma distribution x
right...you then revised this later in the video and I just found it. thx!
Well spotted! Sorry I didn't get it right first time - that's why it's always important to check the samples actually look like the distribution you were aiming to produce.