Questions tagged [sample-size]
This tag is ambiguous. Use it when the question is about sample size and NONE of the following are more appropriate: [small-sample], [large-data], [statistical-power], [underdetermined], or [unbalanced-classes].
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How to calculate required sample size for desired false negative rate
I'm trying to design a system that does some binary classification. The cost of a false negative is high, so I want to ensure that I've tested thoroughly enough to minimize this chance. I would like ...
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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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5 vs 3 measurments of one parameter
Hellow, smart people of the internet,
I have a question: We are doing a study of 170 people- where 20 parameters will be measured 3 times over 2years and the median of every parameter will be compared ...
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Assessing the Implementation and Performance of a New Biomarker in Cancer Surveillance
In a surveillance program designed to detect a specific type of cancer in a high-risk population, both biomarker A and ultrasound (US) are used semi-annually. If either A or US returns a positive ...
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Sample Size: Cluster Randomized Trials
I seek a peer check on my approach in calculating the sample size for pair-matched or stratified cluster randomized trials assuming 80% power.
Some background on the study: I am working with ...
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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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Group Sample size
I have a group of n items that should ideally be homogeneous, although there may be some variability. I need to determine how many items I should sample and test to validate the entire group. I assume ...
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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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Selection of reasonable Power and Alpha for Sample Size calculation
I'm performing an A-B test which involves response rates to communications sent out to customers. I'm looking to calculate a required sample size, and I don't know the expected response rate of the ...
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How to know what sample size (number of cells) is sufficient to determine what percentage of cells are above a threshold?
I have a samples with different cell types (one cell type is shown above). I have calculated for each sample and cell type a threshold signifying non proliferating vs proliferating cells. Cells above ...
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Considering 96 observation for estimating the intercept (rule of thumb)
I remember Prof. Frank Harrell stated that in order to calculate the sample size using the rule of thumb, we must include 96 observations for just computing the intercept, hence the estimated sample ...
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What is the correct sample size for the purposes of this test?
$X_i$, $i = 1, \ldots, n_X$, are i.i.d. from some distribution; and $Y_j$, $j = 1, \ldots, n_Y$, are i.i.d. from some other distribution. Consider all pairs $(X_i, Y_j)$. The number of pairs is $n=n_X ...
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small sample size (need some advice)
I have a prospective longitudinal study. We track and observe a group of people over a two-year period to learn about their cognitive ability. The event variable is binary, and the primary aim is to ...
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How to measure Statistical Significance for calculated Sensitivity, Specificity, Precision, Accuracy and f1 values?
I am trying to understand how to calculate one or more measures of statistical significance to display alongside metrics I've calculated from my data.
Abbreviations I am using in the rest of this post:...
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Sample Size for Logistic Regression
I'm carrying out multiple logistic regression with three independent categorical variables each with more than two categories per independent variable.
I want to use the EPV (events per variable) ...
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