Questions tagged [statistical-power]
Is a property of a hypothesis testing method: the probability of rejecting the null hypothesis given that it is false, i.e. the probability of not making a type II error. The power of a test depends on sample size, effect size, and the significance ($\alpha$) level of the test.
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Sample size calculation clinical trial
I am trying to replicate a study about a randomized clinical trial. For this purpose I want to obtain the sample size calculation the authors did. In the paper they say:
Assuming a reduction of the ...
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Power analysis for the Cox proportional hazards model
I'm trying to work out the sample size needed for an RCT based on a small study looking at reoperation following index surgery. In this small study, there were 1000 patients, group 1 had 700 versus ...
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Issues with Detecting Negative Change in AR(1) Model Using CPAT Library
I'm currently working on evaluating the empirical power of the CUSUM, Rényi CUSUM, and Erdős-Darling tests for detecting change points in AR(1) models, specifically focusing on changes in the mean. ...
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Power of One Sided t-test
Let $X_1, \ldots, X_n$ be a sample from $N(\mu, \sigma^2)$ for unknown $\mu \in \mathbb{R}$ and unknown $\sigma > 0$. Fix $\mu_0 \in \mathbb{R}$. The one-sided hypothesis is $H_0: \mu \leqslant \...
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R: How to calculate power to detect a change in mean beta reg.?
I'm interested in calculating the power to detect a change in my mean response variable by a certain effect size, but I'm not sure how to start. My Y variable is mean plant cover 0-100% cover (mean of ...
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How to do a power analysis on density (count/area) data?
I would like to calculate the power to detect a hypothetical x% decrease from a mean value, but have a few qualifying questions. The data are strictly positive, right-skewed, continuous data ...
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Two-Way repeated measures ANOVA with multiple data points per measurement
I would like to perform a study with physicians of three levels of experience. They shall perform a task under three different conditions. For each condition, the task is performed multiple times (e.g....
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How to combine intention-to-treatment randomization with block randomized experimental designs for within-differences in Power Analysis
I want to calculate the power for my experiment. Within multiple blocks of similarities (e.g., same gender, same pre-treatment outcome), respondents get the opportunity to take part in a treatment. As ...
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is the likelihood ratio test "best" for finite samples?
Wikipedia says
The Neyman–Pearson lemma states that this likelihood-ratio (lr) test is the most powerful among all level α alpha tests for this case.
Is this only true for infinite sample sizes? Is ...
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Chi-square power with (heavily) unbalanced proportions
I want to calculate the statistical power of a chi-square test with (heavily) unbalanced proportions.
I have a variable that I analysed for a sample and whose distribution I know in the population, ...
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Power estimate for an interaction term in factorial design
I am trying to estimate power for a factorial design (2x2).
My initial approach was to estimate pair-wise minimum detectable effect sizes : i.e., if I know sample size, allocation to each group and ...
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Why should you want to use a smaller control group?
In an RCT with multiple treatment arms, I heard that the "pure" control group be small to if we expect the effect size to be large. Why would this be the case? I understand that we could ...
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How to perform a power analysis for poisson distributed data
I want to perform a simplified power analysis to determine how many cells (samples) to have in control and experimental conditions (assume equal n across conditions). For an alpha level of 0.05, 0.95 ...
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z score total for fixed alpha and beta in sample size calculation of mean differences
Can someone explain in detail how $z_\text{total}=z_{\alpha} + z_{1-\beta}$ in a one-tailed hypothesis test of mean difference $\mu_1 - \mu_2$ with common variance in order to determine sample size.
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Power calculation with a binary outcome (using a R package & manual simulation)
I am trying to compare three different methods for power calculation under the same setting. Although I understand that the power estimates from each method cannot be exactly identical due to ...
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