We considered a simple model describing recent fluctuations in effective population size in two or three discrete epochs as well as the single epoch constant size (null) model (see Figure 1).
In this example the N-method was unable to detect any hotspots, whereas the Q-method detected false hotspots on chromosomes 3, 6, 8, 9, 12, and 16. Figure 1, B and C, shows the hotspot size null distributions and the 5% significance thresholds for the N- and Q-methods, respectively.
Recently, Subramanian and Simon [ 46] compared several re-sampling techniques for assessment of accuracy of risk prediction models, and their investigation covers various settings, including sample sizes, null model, number of k-fold partitions, etc.
Only a minority of the trials reported statistical considerations such as sample size calculation, null and alternative hypothesis, significance level, and power.
Sample size calculation: Null hypothesis H1: Sample size calculation for the Mann–Whitney U test was performed according to Noether [ 26] under the assumption of a normally distributed outcome variable [ 26].
For a given a nuclear family size, the null model also predicts the proportion of all cases that are part of a cluster and the average number of cases per cluster.
Fifth, the confidence intervals around our estimates for TV viewing were quite wide, suggesting that, due to our relatively small sample size, the null findings in this study could be the result of a Type II error.
The Q- and N-methods, with observed GWER (red), and target error rate (black), have two α-levels, α1 for QTL mapping and α2 for the tail area of the hotspot size permutation null distribution.
Despite this difference in size, SirT1-null mice eat similar or only slightly less food than controls (Figure 1B).
This result is in line with small effect sizes or null results from population-based studies [ 19 21, 23], suggesting that the ACE effect is at best weak.
These problems can be partially solved by using the isolation model with unequal population sizes as null model (see Methods for details).
