Questions tagged [sample]
a sequence of objects or individuals collected from a larger (possibly infinite) population or process.
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How to do rarefaction analysis for sample-based abundance data?
I would like to compare plant richness of different forest stands via rarefaction. The data is collected in a plot-based manner. I set 4 equal-sized plots in each stand, counted all plant individuals ...
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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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cloglog.sample.size function (Binomial distribution)
I was wondering if cloglog.sample.size function from binom package in R can be used to calculate the sample size for the following model (Binomial dis with cloglog) which can be used for discrete ...
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Standard deviation on result of calculation
I'm calculating a value based on experimental data. The calculation is
$$ k = \frac{a - b}{c} \cdot \frac{1}{T}, $$
and $a$, $b$ and $c$ are all measured experimentally, multiple times, with some ...
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Calculating the value of Cox-Snell Rsquared
I want to calculate the minimum sample size for a prospective longitudinal study (using cox regression - the aim of the project is prediction). The following function pmsampsize from the pmsampsize ...
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Sample size for Survival Analysis (Cox regression) with discrete time
I have a study where the patients come to the hospital every two months for check-ups. T0 ( one week before surgery), T1 (two months after surgery), T2 (4 months after surgery) up to T9 (18 months ...
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Sample size for REPEATED MEASURES ANOVA
I am calculating a required sample size for the Repeated Measures ANOVA (within subject). I came across two different packages and the results are different.
Using "WebPower" package and the ...
anna eyre
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Sample size for survey
My interest is to perform a statistically significant survey on a population of 1700 people, that can be described in different categories, so each person belongs to only one category.
I have two ...
user412668
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Random sample and its underlying sample space [duplicate]
A random sample of size $n$ is a random vector $X=(X_1, ..., X_n)$, where all $X_i$ are i.i.d., and are measurable functions on some sample space $\Omega$.
Let's say, $\Omega = \{H,T\}$, i.e., heads ...
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Calculating sample size for comparing pretest and post-test scores
I am trying to evaluate a new curriculum. I intend to do it by giving students a test at the beginning of the academic year (pretest) and one at the end of the year (post test).
There are roughly 50,...
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What is the meaning of confidence intervals when NOT using sample data and instead have data on the whole population? [duplicate]
I'm trying to understand why you would need confidence intervals or compute statistical tests (for comparing proportions) when your data is NOT from a sample and you have data on the whole population.
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Robust estimation of standard deviation using relatively small sample taken from a Gaussian distribution
I'm sure this question was asked before, but I don't seem to be able to find a convincing answer.
If there is a relatively small set (say 3<n<20) of observations of a quantity that is assumed to ...
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Clarifying between sample date and input data
I'm reading section 2.6.3 from the book "The Elements of Statistical Learning" of "Trevor Hastie",
"Robert Tibshirani" and "Jerome Friedman" and I have a few ...
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ARIMA model underestimates
What steps should we take if my ARIMAX model consistently underestimates?
Furthermore, should this underestimation be a significant concern in my analysis?
Edit:
I am doing an ARIMAX forecast where I ...
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Terminology clarification about sample moments
According to MathWorld (link): "The sample raw moments are unbiased estimators of the population raw moments".
While in Wikipedia (link) it is said:
...the $k$-th raw moment of a population ...
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