The statistics tag has no wiki summary.
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1answer
109 views
Lacking of scale and distribution moments
Given a physical random variable x, $E(x)$ and $E((x-<x>)^2)$ defines mean and variance. From a statistical point of view variance represents the statistic error (isn't it?). If variance is not ...
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0answers
51 views
Fitting of data to a model
Imagina that I have some observable value predicted with a theory for some process to be:
1+a x + b x^2 and observed value is 1.3 with an error 0.2; a and b are some numerical constants. I also have ...
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1answer
63 views
The discrepancy between the two values in units of sigmas?
Assuming gaussian error distributions, how to calculate the discrepancy between the two values in units of sigmas?
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1answer
81 views
Variance of Nested Experimental Uncertainty
I have to find the uncertainty of a quantity $Q$ doing two mean values. For example for a set of parameters I measure ten times $Q$, I obtain a mean value $Q_1$ and variance ${\rm Var}(Q_1)$. Then for ...
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2answers
284 views
Relating the power to weather variables [closed]
Could you please help me in this problem?
I have 3 independent variables, (T,H,t) , as inputs and one output P ( I have all data for these inputs and the output, done experimentally measured every ...
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1answer
873 views
How to combine the error of two independent measurements of the same quantity?
I have measured $k_1$ and $k_2$ in two measurements and then I calculated $\Delta k_1$ and $\Delta k_2$. Now I want to calculate $k$ and $\Delta k$.
$k$ is just the mean of $k_1$ and $k_2$. I thought ...
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1answer
961 views
Is there a stable numerical algorithm for FWHM that isn't 2.35*sigma?
This is a question that should have a simple answer, but which I can find no proper discussion of in the literature or on the internet.
I start from the assumption that I have a noisy numerical ...
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1answer
226 views
Is $\sigma$ or $\sigma / \sqrt{N}$ is error of a measurement?
I wonder whether $\sigma$ or $\sigma / \sqrt{N}$ is error of a measurement. When I measure, say $0, 1, -1, 1, -1$, I have a $\sigma = 1$. I just measure $0, 1, -1$, I also have $\sigma = 1$.
But in ...
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2answers
119 views
Question about uncertainty
Are $3.43\pm 0.04$ $\frac{\mathrm{m}}{\mathrm{s}}$ and $3.48$ $\frac{\mathrm{m}}{\mathrm{s}}$ within expected range of values?
The answer is yes, but I do not clearly see why this is so. I appreciate ...
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3answers
862 views
How to combine measurement error with statistic error
We have to measure a period of an oscillation. We are to take the time it takes for 50 oscillations multiple times.
I know that I will have a $\Delta t = 0.1 \, \mathrm s$ because of my reaction ...
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0answers
149 views
What statistical test should I use?
I have two differential cross sections $d\sigma_{1,2}/dM$ ($M$ is some invariant mass) corresponding to different hypothesis. What I want is to calculate how well the appropriate experiment would do ...
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3answers
349 views
Calculating uncertainties for a final result
Say you are dividing 2 times with uncertainties:
$$\frac{t_1}{t_2} ~=~ \frac{0.551s \pm 0.002s}{ 0.712s \pm 0.002s}.$$
After doing the calculations you get:
$$\frac{t_1}{t_2} ~=~ 0.774 \pm ...
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1answer
57 views
How to properly read a measurement result if it is a number?
If the result of a measurement is i.e. $3.2 \pm 0.7$, what is 0.7? At which confidence level we know that the real result is inside of this interval?
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3answers
78 views
Statistics software for basic undergrad lab
I'll have to perform some simple experiments, like measuring the period and damping of a pendulum, focal length of a lens, …
As a result I will end up with some X, Y data points and need to calculate ...
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1answer
348 views
What's the meaning of negative accuracy for measurements of physical quantities?
What's the meaning of negative accuracy for measurements of physical quantities? Can measured values of a physical quantity ever have a negative accuracy?
I read some materials about accuracy and am ...
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3answers
418 views
Can Planck's constant be derived from Maxwell's equations?
Can mathematics (including statistics, dynamical systems,...) combined with classical electromagnetism (using only the constants appearing in chargefree maxwell equations) be used to derive the planck ...
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1answer
176 views
Finding coefficient of proportionality
Recently in my AP Physics class I did a lab in which I measured k for a spring by setting up an oscillating system with it, and timing the period, repeating for different masses. Since ...
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2answers
115 views
More data points or more averages?
Perhaps an elementary questions. Given a time limited measurement situation, would it be better for one to measure more averages or more data points?
More averages will increase the SNR by ...
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2answers
205 views
How do derive this result in stat-mech style
I'm going through (well, at least I'm planning to) Rief's book about statistical mechanic (I want to improve my knowledge). I want to be serious about this so I'm trying to solve as much problem as I ...
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6answers
793 views
Why don't experimental physics groups have statisticians in it?
Perhaps someone can clear up a bit a cognitive dissonance I am experiencing. Pollsters are under constant scrutiny of statisticians for even the most mundane of survey topics. With so much riding on ...
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1answer
2k views
Standard Deviation in Particle Physics
I'm familiar with sigma, and how its usually calculated and used, but would like to know how it's applied to particle physics. I recall reading that the discovery of the Higgs would only be credible ...
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2answers
279 views
Photon statistics of an incandescent light source
We usually calibrate the cameras on our microscopes by capturing 20 images of a blurry (not sharp) fluorescent particle. For each pixel in this stack of 20 images we calculate the intensity variance. ...
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220 views
How to predict how much data to collect
The same question on CrossValidated
Apologies if I'm being a bit vague in what follows, I've been asked to keep certain aspects of the experiment confidential for the time being.
An analogous ...
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1answer
143 views
Products of Gaussian stochastic process variables
In the classic experimental physics text "Statistical Theory of Signal Detection" by Carl. W. Helstrom, Chapter II, section 4 concerns Gaussian Stochastic Processes. Such a process is observed at ...
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1answer
350 views
Metrology: What is precision for a measurement? [closed]
Is precision a "quality" of a measurement?
Is there a better (accepted by the literature) word?
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1answer
287 views
Astronomical detection significance from magnitude error
At this website:
http://heasarc.gsfc.nasa.gov/docs/swift/analysis/threads/uvot_thread_afterglows.html
The passage at the bottom states that a V-band magnitude of 17.62, with an error $\pm$0.02 is a ...
