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Questions tagged [data-analysis]

Use for question relating the the techniques of data analysis.

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Signal parameter estimation in PyCBC

I have a gravitational wave signal (strain vs. time). And I want to find out the corresponding parameters of the compact binary. But I do not know how to create injection for this signal in PyCBC. ...
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What Dimensionality Reduction method I can follow on a dataset that has Physics Parameter?

I am trying to model data related to Locomotive Train. We have a various set of parameters and we have the possibility to generate a few more parameters from this. Our model is currently using a lot ...
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1answer
27 views

Power law correlation between with three parameters

I made a CFD model of the Centrifugal Atomization Process. Studies show that the mean particle size $d_{32}$ can be expressed as a function of the three operating dimensionless numbers (Reynolds, ...
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1answer
28 views

Normalize accelerometer data based on non-central location

I am trying to "normalize" accelerometer data for a sensor that is not centered on a car. In the image below, you can see how centripetal force changes based on location. In my case, I only have one ...
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1answer
32 views

What is the meaning of true value and uncertainty from a measurement?

I am taking the following example: Lengths of an object are measured as : 5cm , 5.2cm , 5.1cm , 5.5 cm. Calculate the true value and the error . The answer is True value = 5.2 cm error = 0.15 ...
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Why is the resolution or measurement uncertainty of $G$ so bad?

I sorta know how the Cavendish apparatus works, and I know that "Gravity is an extremely weak force" for subatomic particles in comparison with the E&M or nuclear forces that act on these ...
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Uncertanty in Chi-squared measurements, spectra-like

Let's say I have some observational data. For example: in a certain wavelength interval I measure the flux, 10 000 points, and I have the uncertainty for each one of them. For example: ...
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4answers
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How do I fit a resonance curve?

In an experiment, I collected data points $ (ω,υ(ω))$ that are modeled by the equation: $$ υ(ω)=\frac{ωC}{\sqrt{(ω^2-ω_0^2)^2+γ^2ω^2}} \,.$$ How can do I fit the data to the above correlation? And ...
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How do we know the LHC results are robust?

Nature article on reproducibility in science. According to that article, a (surprisingly) large number of experiments aren't reproducible, or at least there have been failed attempted reproductions. ...
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Visually comparing variances

I have a dataset containing 8 categories, I now want to visually compare the variance between the categories. The most common approach would be to use box plots or violin plots but I would like to ...
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1answer
27 views

What is BVI Photometry and how is it used?

I searched for data about Cepheids light curves (often used as standard candles for measuring distances), and found that all of the data comes in a form of "BVI Photometry" or "BVI Photoelectric ...
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1answer
35 views

Origin of XRD Peak Asymmetry

I have been doing an introductory XRD experiment in which we measure the crystal spacing of a simple lattice (LiF) and as usual obtained data for intensity against two theta. Ideally the peaks should ...
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2answers
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Do I force the intercept to zero when determining the coefficient of friction?

I have made these measurements of kinetic friction force vs normal force: I want to measure the coefficient of friction as the slope of the line. Unfortunately the line does not pass through $(0,0)$. ...
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Mathematical Resolution of Overlapping Signals

I would like to take the opinion of physicists (my area is chemistry). During instrumental analysis, the output is a instrument response vs. time. Each peak corresponds to a molecule which is ...
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26 views

Why is this version of Fourier deconvolution justiifed?

As I understand it, one typically performs Fourier deconvolution for the data produced by some instrument of a linear system by: Taking the observation of some unit impulse signal $m$, with the ...
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1answer
45 views

Error propagation and data linearization

I am fairly new to teaching error propagation to students but came across a question I couldn’t answer myself. Say we have a set of data that produces a parabola. In order to linearize the data and ...
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2answers
77 views

Big Data Handling at the LHC

My understanding is that much of the data that is is collected at the Large Hadron Collider is similar to that in the image below, and that a vast amount of the data contains little of specific and ...
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How to Mathematically Compute Spectral Power Distribution for Each Visible Wavelength in Spectrum?

I'm a CS student and been working on a conversion program that includes computing Spectral Power Distribution (SPD) from each visible wavelength in color spectrum. Here's the formula : $$X = \int_{...
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Observed Data for Asteroid Lightcurve

I am looking to find out more about writing statistical analysis programs in python for astronomy problems and was recommended that I could analyse asteroid light curves for an introduction into the ...
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7answers
1k views

When to average in the lab for indirect measurements?

I am measuring distance and time to calculate the velocity. I repeat the experiment 10 times. What is better, to first calculate the average of distance and time and then the velocity, or to calculate ...
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0answers
35 views

How to fit mean squared displacement data from nanoparticle tracking analysis?

I am trying to independently analyze raw nanoparticle tracking analysis (NTA) data, but my diffusion coefficients calculated directly from x and y pixel values only moderately correlate with reported ...
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1answer
77 views

Double slit experiment/ fitting data to complicated sine function and vice versa [closed]

As part of analysing the double slit experiment, I've recorded position values for a number of minima and the central peak position. Also, I've conducted a single slit experiment (with unknown width)...
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2answers
66 views

Removing zero-counts in exponential decay measurement

I'm doing an experiment where I'm measuring the mean-lifetime of muons. I have a set of data points for the number of decays against time, resembling an exponential distribution (of course). But in ...
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Where to find databases from physics experiments?

In some lecture I want to write about data analysis in physics I want to show some real uses of data analysis tools in the analysis of data from real experiments. I tried to search but I couldn't find ...
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1answer
34 views

What do the points on a Dalitz plot represent

I have read that a Dalitz plot is nothing but the plot of $m_{12}^2$ vs $m_{23}^2$, and that the dots correspond to "events". However, this doesn't really tell me anything. My question can boil down ...
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2answers
69 views

Estimate of the period of noisy “event counting” data

I have a set of experimental data, which come from a periodical event. More specifically, these are detections from a single photon detector, so there is no intensity, I only have the timestamps of ...
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Data-analysis (Uncertainty and errors)

This is just a data anlysis question but I thought you might need an introduction. In order to calibrate de Michelson interferometer one needs to find $\eta$ in the relation: $d = \eta D_\mu$ where $...
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1answer
33 views

File with particle decay data [closed]

Does anyone know of a computer parsable file that has basic physics and decay data for (quite many) observable particles, such as mesons, barions, heavy leptons and $W, Z, H$? To clarify the data I ...
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Does the vertex efficiency include track reconstruction efficiency?

Consider a document of ATLAS collaboration on displaced vertex level efficiency. On the first two pages there is a description of cut-offs required to background free displaced vertex reconstruction. ...
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1answer
50 views

What is the significance of a $\chi^2$ analysis?

What is the merit of $\chi^2$ analysis in the laboratory experiments? Why is so much emphasis put on it?
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1answer
219 views

Binning or just skipping values in a simulation to avoid autocorrelation

Given a set of data from a generic Montecarlo simulation $x_i$, $(1=1,...,N)$, autocorrelation is expected to happen between data points within relaxation time $\tau$ (correlation time) distance ...
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1answer
104 views

Jackknife estimation of variance very different from expected variance

I was rapidly introduced to the Jackknife procedure for data analysis and I stumbled upon a problem I'm not able to understand. Let's consider a very simple case: the estimation of the average of a ...
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2answers
79 views

Is there any experiment that doesn't have a finite countable number of outcomes?

There are a lot of random variables in physics that are, in principle, continuous and unbounded (canonical examples: time, position along each direction). In practice, it is my understanding that the ...
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0answers
113 views

Exclusion limits on particle dark matter

I'm trying to make sense on how the upper limits of the cross section of particle dark matter (WIMPs) are computed, like in the figure below. This is taken from an article on dark matter searches. ...
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1answer
51 views

Determining Threshold Voltage and Plateau from experimental data

I’ve been trying to figure out how to interpret the following data from the Geiger muller tube There are only seven data points. Where does the plateau begin? Has the data collection begun after the ...
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1answer
37 views

Tracking efficiency for experiments at CERN

For various experiments (e.g. ALICE, CMS etc) at the CERN-LHC, people talk about tracking efficiency. What exactly is this tracking efficiency? How different is it from reconstruction efficiency?
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1answer
84 views

Convergence tests for experimental data

I ran a simulation for the critical density at which traffic flow transitions from laminar flow to start-stop-waves. The results for different road lengths are: From the graph we can see that the ...
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0answers
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Question about statement of uncertainty

I have a doubt about uncertainty of a measurement. I have a sample of a specific material which is my reference material and it is calibrated and NIST traceable. This sentence is in its data-sheet: ...
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0answers
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What are common methods to remove discretization on experimental measures?

I have some experimental data, and since the measurements are digital, the data is discretized/quantized/rounded/truncated. I need to know if there are general methods, or common methods, to "smooth" ...
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1answer
109 views

What causes the 20 second period in LIGO data?

I download LIGO data on GW150914 (gravitational waves) via the code in Mathematica ...
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774 views

Parallel Axis Theorem Experiment

I am currently working on a physics experiment to confirm the parallel axis theorem. To do this, I have the following setup: In this experiment I change the distance between the centre of the ...
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1answer
615 views

Moment of Inertia and Mass Experiement

I am currently working on a physics project to experimentally confirm the relationship between mass and moment of inertia. The experiment is setup as depicted: In this experiment, $r1$ and $r2$ are ...
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49 views

Correlations and associativity

Suppose one has a set of data $D$ and a theoretical model $M(A,B,C)$ one wants to fit to it by obtaining the best fitting values of the parameters $A,B,C$, which in principle are free. Plotting the ...
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1answer
28 views

How to find average in this case?

If we have 10 trials of measuring density each repeated three times. How can we find average? Do we take the average of each trial and then find the average of the averages? Would this be physically ...
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0answers
43 views

Uncertainty of interpolation when covariance matrix is given

Assume that there is a given covariance matrix of an evaluated quantity ( in my case it's a rection cross section $\sigma = f(E)$, where $\sigma$ is the cross section and $E$ is each energy point ...
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3answers
647 views

Uncertainty in counting population? Vs uncertainty in measuring length?

I know that when I use a ruler to measure the length of a table, an uncertainty will be the finite width of the ruler's markings. What about when counting people? Say I count the number of people ...
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2answers
77 views

Consistency of data

In particle physics, what factors do we consider to conclude that the measurements done by two different experiments are consistent with each other? (You may even explain the concept with an example)
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2answers
66 views

Experiment on friction coefficient

Here you can see the results of the experiment about a friction coefficient: The mean of the friction coefficient becomes 0.262 but when I do a linear regression in the form of y=mx the slope is 0.31....
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2answers
140 views

How to analyse gamma ray spectra?

I have recently done an experiment using gamma radiation and am now at a loss as to how to analyse the data I acquired. I have a background spectrum and a spectrum from a radioactive sample and need ...
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Can a particle be identified when one knows $\left<dE/dx\right>$ and the Cherenkov angle $\theta_c$?

I have a question about if it would be possible to identify a particle by measuring the energy loss due to ionization $\langle dE/dx\rangle$ and the Cherenkov angle $\theta_c$. I assume that we know ...