# Search results

1. ### 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. ### 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...
3. ### Ratio of sizes data

So I have data regarding the ratio of a cell organelle (the Golgi) to the overall cell size from 48 cells, each one belonging to one of 3 genotypes. I want to investigate whether this ratio is influenced by genotype. My first thought was simply to perform ANOVA on the data (or a Kruskal-Wallis...
4. ### Interpreting coefficient of determination from kappa estimate

Hi all, According to this article taking the square of a kappa statistic gives an approximation of the coefficient of determination and is more interpretable than the kappa value alone. But I'm not sure. Say I have a kappa of 0.80, the CoD is then 0.64. Could I then say that 64% of the...
5. ### Meta-analysis of kappa statistics

I'm looking at doing a meta-analysis on the reliability of a few pathology outcomes. I'm trying to follow the method set out in this paper as the reliability is usually measured using Cohen's Kappa. So far just a couple of questions. 1). Some papers I look at report a weighted kappa statistic...
6. ### Unbalanced, non-normal, heteroscedastic ANOVA alternatives.

I wanted to compare the means of 4 groups, all of which with a different number of observations. None of the group residuals are normally distributed (nor their log-transforms) and they are also heteroscedastic: at worse the SD of one group being about twice that of another. ANOVA, including...
7. ### Brownian motion around a sinusoid.

I wish to model arrivals of people into a healthcare queue. The methods I have studied involve assuming that the arrival rate is constant - but the data clearly show this is not true, it shows a sinusoidal pattern. I was thinking of fitting a sinusoid to the data (using least squares), then...
8. ### Dispersion parameter

I have the understanding that the dispersion parameter, \phi, in generalised linear models needs to be known for deviance to meaningful or otherwise it can be estimated from the model, but no analysis of deviance can be carried out. Why is it then that in binomial and poisson models in R/S+...
9. ### Variance and the second moment

Need some help understanding some basic concepts. I understand the first moment of a distribution as being a central point about which the distribution balances. Is this a correct understanding? I cannot visualise any higher moments though, not even the second moment. It seems to be...