Recent content by Prometheus

  1. P

    Variation of biological and technical replicates

    I want to find the standard deviation of three groups each that have each been exposed to different factors (i.e. biological replicates). The problem is that each group was constructed of technical replicates. These technical replicates will have a variance. The biological replicates will also...
  2. P

    Is it possible to test this moderated multiple mediation model?

    So you've got 3 types of leadership style of want to see their effect on learning motivation? How is learning motivation measured? And you have perceived workload as a covariate? How is this measured?
  3. P

    T Tests to compare feeding rates of 3 sugars?

    Look into repeated measures ANOVA - it might do. Otherwise maybe look into something like finite difference, but them since you've got three time points you actually have 2 feeding rates. You could assume a linear rate - if that makes biological sense. Look into the literature, someone must...
  4. P

    2 way ANOVA and non-parametric alternatives

    Ah yes, i vaguely recall GLMs. I'll have to read up on it. Would the fact that the data is a ratio make this more tricky. I was thinking initially maybe a 2-way ANCOVA, the numerator kept as the IV with the denominator a covariate.
  5. P

    Sample size calculation for cohort study

    But what does 'sufficient for analysis' mean in this context? Are you really trying to establish the efficacy of some treatment? Or are you trying to see if the study is feasible? You shouldn't get a p-value just for the sake of having one. What would you want to show in your analysis?
  6. P

    2 way ANOVA and non-parametric alternatives

    I want to compare 4 groups: (treatment 1 tissue type 1), (treatment 1 tissue type 2), (treatment 2 tissue type 1), (treatment 2 tissue type 2). I'm mostly interested in any difference between treatment groups, but anticipate there may be an interaction with tissue type. Initial thoughts are to...
  7. P

    Mean time between failure caused by natural death

    My memory is a little hazy on this, but i believe something like Cox regression can deal with, which if i understand you correctly is essentially the same as right censorship. Check out survival analysis too. Hopefully that'll give you something to google before a grown up answers.
  8. P

    Sample size calculation for cohort study

    If it's a feasibility study do you really need a power calculation? You might, but the purpose of a feasibility study is to assess the feasibility of the methods, not to establish some statistical difference (although you can use the numbers you get from the pilot in the power calculation for...
  9. P

    Best statistical treatment to finding relationships between two variables... and how to do it.

    How is netiquette measured? What even is netiquette?
  10. P

    Stat HW help

    So you have many groups of animals and want to test whether they have the same levels of nickel (per some unit of blood?). Sounding like an ANOVA type problem so far.
  11. P

    Algorithms for Spawning in Multiplayer games

    I guess you could try to minimise some objective function for each spawn point, that function being somehow weighted by density of enemies such that it penalises both being too near and too far. Not sure ML techniques would be useful though. For instance a SVM is a supervised technique - you'd...
  12. P

    Which test to use

    My first thought was a logistic regression model, but the fact fluorescence was different for some of the interventions might be tricky. Does it make sense to pool the signal into low and high intensity? Then you could try multinomial logistic regression. Should also be easy to add...
  13. P

    Ratio of sizes data

    I've been using this as a guide to ANCOVA in r. Turns out that my model violates some the assumptions of ANCOVA (numbers 3 and 4 in the link). In particular the covariate, cell area, is different between some of the genotypes. The variances are also not equal. I am a little confused because...
  14. P

    Ratio of sizes data

    Thanks for the correction. Yes it is how Golgi size changes with 3 different genotypes i want to examine, but Golgi size is also related to cell size so it's the relative size i want to examine. It is unclear at this point whether the 3 genotypes influence cell size as well. I'll give ANCOVA a...
  15. P

    Ratio of sizes data

    I'm now wondering whether ANCOVA is the way to go with this with Golgo area as the independent variable and cell area as a covariate. Thoughts?