Mathematics Stack Exchange
Mathematics Stack Exchange

Questions tagged [statistics]

Mathematical statistics is the study of statistics from a mathematical standpoint, using probability theory and other branches of mathematics such as linear algebra and analysis.

Statistics is the science of the collection, organization, and interpretation of data. It deals with many aspects of data, which includes the planning of data collection in terms of the design of surveys and experiments. (From Wikipedia)

More specifically, mathematical statistics is the study of statistics from a mathematical standpoint, using probability theory as well as other branches of mathematics such as linear algebra and mathematical analysis. (From Wikipedia)

For questions which are more generally about collecting and treating data, it is advised that you post your question on Cross Validated and DSSE.

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How many LinkedIn connections would I need to be 2nd degree with everyone

A mental experiment, If I would want to be a 2nd degree connection (only 1 person in between me and another one) with everyone on LinkedIn, how many connections would I need to have? I found these number: 722 million users in total…
Phalox
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In what interval must the percentage of black squares fall in order to capture 95%, 99%, and 99.9% of possible QR codes?

Generally speaking most QR codes look as though they have about 50% of their cells black. If a putative QR code had 90% or 10% of its cells black, we would reasonably conclude that it didn't look like a QR code. Centred on the mean, which may…
user583837
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Simple question about histogram

Wikipedia article about histograms says following: A histogram is a representation of tabulated frequencies, shown as adjacent rectangles, erected over discrete intervals (bins), with an area equal to the frequency of the observations in the…
radha
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Voting intention poll

In a voting intention polling, we use a a random sample of 400 people and the two candidates, party A and party B get 32% and 28% respectively. Check whether party A will win against party B with probability 99%. I assume that, by "probability"…
Juan Manuel Prada
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Could finding the central tendency between mean and median be useful?

I'm working with unpredictable data, it could have strong outliers in some cases, and not in others. Considering it's completely situational and random, would it make sense to just average the mean and median of the dataset to get the best of both…
srb633
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if a scatter plot is above a given equation, is it a bad fit

So, a friend of mine asked for help with a question concerning scatter plots. She graphed it out and looked like To me, it looked like a good fit. However, other friends said that it was wasn't a good fit because all the data is above the…
ninjagirl
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What measure of distance does the harmonic mean minimize?

The arithmetic mean of a set of numbers minimizes the squared error. The geometric mean minimizes the squared log difference $\left[\log(x)-\log(\overline{x})\right]^2.$ The median minimizes the mean absolute error. What does the harmonic mean…
Gavin
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How to find mode when modal class is first or last class?

We know that formula of finding mode of grouped data is Mode = $l+\frac{(f_1-f_0)}{(2f_1-f_0-f_2)}\cdot h$ Where, $f_0$ is frequency of the class preceding the modal class and $f_2$ is frequency of the class succeeding the modal class. But how to…
Sumit Kumar
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What is the UMVUE of $\exp(-2\lambda)$ for X is a random variable with poisson distribution~poisson $(\lambda)$

If $X_1,X_2,…,X_n\sim Pois(λ)$, find the UMVUE of $\exp(−2λ)$. I know based on lehmann scheffe theorem, the step is (1)find $q(x)$ an unbiased estimater of $\exp(−2λ)$ (2) $T(X)$ is sufficient and complete (3) $s(*)=\mathbb E(q(x)|t(x))$ is a…
Grace
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Let $X$ and $Y$ be random variables. Suppose $f_{X,Y}(x,y)=g(x)h(y)$. Prove that $X$ and $Y$ are independent.

Let $X$ and $Y$ be jointly absolutely continuous random variables. Suppose $f_{X,Y}(x,y)=g(x)h(y)$. Prove that $X$ and $Y$ are independent. So I want to show that $f_X(x)=g(x)$ and that $f_Y(y)=h(y)$ And I have that $$\int_{-\infty}^\infty…
AColoredReptile
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Wording of a statistics question

Apologies if this is not the correct area to post this but, I have a question about the specific wording of an assignment. We have been given this sentence, basically The occurrence of false positives [in some experiment] is 40% What does this…
Gabe
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Why do we subtract the variance?

This is not a question for doing my homework. This is a question to understand the deeper meaning of the answer. So in part b), it subtracts the variance. Why do we subtract variance and what does it mean to subtract variance? I understood variance…
Strawberry
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Chi-Square goodness-of-fit test on sample space or quantiles?

I think there are two ways to perform the chi-Square goodness-of-fit test: Divide the sample space into bins of equal size and see how many observed values fall in each bin. where the expected per bin depends on the fit. Divide the cdf of the fit…
Wuschelbeutel Kartoffelhuhn
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Can someone explain to me the intuition for the formula for finding the percentile of a value in a data set?

Basically, my math textbook just gave me the formula without any explanation on about the "why"/intuition of the formula. Here's the text from the book: • Order the data from smallest to largest. • x = the number of data values counting from the…
Joe
  • 485
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How to correct/filter inaccurate speeds calculated from a GPS track

I am working on a simple application that allows the user to do a lot of different things with a GPX file (GPS track). Some things computed are: average speed, max speed, etc. The max speed values I'm getting are very unrealistic, and when I look…
The111
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