# Tagged Questions

Questions about the statistical process of sampling from a population, in order to obtain information for use in statistical learning, estimation, hypothesis testing about some population or process.

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### Simple Random Sampling: Find the variance

I have trouble answering this simple question. There is a total of 280 trees. The assessed total yield is at 432,6 tons. 25 trees are picked at random and their timber yields are accurately ...
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### Variance of sample mean difference

I have encountered this a variation of this problem as a test task for a job interview. It's been long since I last encountered probability theory, so I couldn't solve it. Still, it deprived me of ...
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### How come uncertainty adds up without squaring it?

I'm currently trying to sum measurement with unknown uncertainty. My plan is to make an experiment and try to measure multiple time the same sample and figure the variance of each of my measurements. ...
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### Sampling the Sin(x)/(x) Function

Say we have $$x_c(t) = \frac{sin(\pi t)}{(\pi t)}$$ $x_c(t)$ has a maximum frequency of $\omega_M = \pi$. According to Nyquist's Theorem, this signal can be perfectly reconstructed from its samples, ...
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### 2 simple statistics questions regarding probability and means.

Fire alarms go off in the engineering building an average of 13 times per year. Find the probability of more than one fire alarm going off in the month of December. For this one, I am uncertain on ...
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### What's the formula to get the x2 in this chi-square table?

I'm just wondering what's the formula to get the x2 answers in this table.
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### Stratified sampling

In general, is there an optimal number of stratas to use when employing the Monte Carlo variance reduction technique: "Stratified sampling"?
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### Generate Uniformly Random Points on a Transformed Sphere

I have a sphere transformed by an affine transformation (represented as a 4x4 matrix). How should I get uniformly distributed points on the transformed sphere's surface? Note that the obvious thing--...
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### Statistics- Why is T being used over Z here?

"In their 1992 study of human internal body temperature, Mackowiak, Wasserman and Levine, their sample mean, x = 98.25 with standard deviation = 0.73, led them to a hypothesis that human internal body ...
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### What does the conclusion with confidence interval mean, non-statistically speaking?

There is a manufacturer who told me that they tested devices in the batch based on 95% confidence level, 5% confidence interval/margin of error and 50% distribution. So from 1500 devices, they tested ...
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### Asymptotically unbiasedness of an weighted estimator

Consider a Markov chain on a state space V with size N, and let $\pi(v_j) = \sum_{v_i \in V} \pi (v_i)P(v_i,v_j)$ be the stationary distribution, where $P(v_i,v_j)$ is the transition probability. ...
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