Questions tagged [data-analysis]
Use for question relating the the techniques of data analysis.
465 questions
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Why does orbital velocity variation correlate with $\sin$ of the angle between position and velocity vectors?
By analyzing the motion of Venus using NASA JPL Horizons ephemeris data (10-year span, 1-hour sampling), I found that the variation of orbital velocity $\Delta v(t)$ appears to closely follow a ...
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1
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Clipping the covariance matrix [closed]
I want to test my anisotropic cosmological model against Dark Energy Survey (DES) data and constrain Right Ascension (RA) and Declination (DEC). The DES data, although containing 1829 data points in ...
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6
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Statistics for Theoreticians
I'm a theoretician, and as the years pass, I notice my knowledge of statistics and my memories of experimental physics classes fading and becoming more and more uncertain. Thus, I'd like to ask for ...
3
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1
answer
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Is it okay if your signal and noise have the same statistical distribution?
Please bear with me if this seems like a very basic question. Let's say you want to detect a signal by measuring a variable $x\in[0,\infty)$. Let's say you know the variable $x$ follows a probability ...
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Numerically marginalizing over a parameter
I am working with gravitational waves data. I have done a Bayesian parameter estimation using dynamic nested sampling. So I have posterior distributions for several parameters. Now I want to ...
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3
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When to average measurement results?
What do I want to do?
I want to measure the gravitational acceleration $g$.
To do so I measure the fall time
of an object from a height $h$, which I have measured previously up to a uncertainty $\...
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4
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1
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363
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Mean time and mean velocity in example with ball running down a slope
I was reading about examples of experiments with a smooth ball over running down a smooth slope and how the concept of velocity was formed.
So as an example if we have a ball that is at $t = 0$ at $d =...
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To what extent is gravitational wave “observation” a function of model-matching?
I'm asking about the epistemic structure of the detection process — not whether gravitational waves are real, but how we decide that what we've seen is a specific event, given that the match is ...
0
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147
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Monte-Carlo error propagation in divergent function
I have a function
$$
f(a,b)=\left(\frac{a}{b} - 1\right)^{-1}
$$
I have obtained values for $a$ and $b$ from two independent linear fits including errors on $a$ and $b$.
Now I wanted to calculate the ...
1
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1
answer
134
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How to interpret fusion rates data from REACLIB1?
I'm trying to model fusion in a star, and I came across a library of reaction rates data: https://reaclib.jinaweb.org/popularRates.php
The rates come as a polynomial in temperature, but the result has ...
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1
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0
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Outstanding Cosmology Problems Needing Better Algorithms [closed]
There are/were open problems in cosmology where we have the tools necessary to study them but not enough data to use. For example, we know how to use strong lenses to estimate the Hubble constant and ...
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What's the naming convention for variables/features in ATLAS datasets?
I am working on my Master's thesis and am working with (simulated) ATLAS data - v09 Ntuples for the hypothesized tbH+ channel. I'll be using FastFrames to process the raw Ntuples and then use the FF ...
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111
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Determination of Ohmic Resistance from Characteristic Curve [duplicate]
When trying to determine the ohmic resistance from measurements of current $I(U)$ at different voltages $U$ of a circuit with the ohmic resistance built in, which of the following methods evaluate the ...
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4
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What is the point of using a least squares fit for experimental data points when almost all data points have varying errors in $y$?
Sorry if this is a silly question - 1st year Physics undergrad here. My question is, why does the method of least squares fitting seem so ubiquitous, given that it is always emphasised that where ...
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4
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286
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How can I detect when a car makes a turn using velocity vectors and account for speed?
I am trying to detect when a car makes a turn by analyzing its velocity vectors over time. Each velocity vector is represented as:
$$\vec{v_t} = (X_v, Y_v)$$
Currently, I calculate the change in ...
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1
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112
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Linearized or nonlinear least squares for Arrhenius: mitigating heteroscedasticity
I have a question that is essentially expanding on this older question, but digging into a specific aspect of it that was not directly discussed
Suppose I have data points that fit an Arrhenius trend:
...
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What would the unit for the slope of a graph where the $x$-axis is mass and the $y$-axis is the drag coefficient?
I have written a paper on the effect of change in mass on the drag coefficient of a ping pong ball. While making my last calculations, I decided to use the slope of the final graph (where the $x$ axis ...
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Verifying Hooke's law through video analysis in a dynamic setup
For educational purposes, I am attempting to experimentally verify Hooke's Law using a dynamic setup analyzed through video footage. In this experiment, a body of mass $m$ is accelerated by a spring. ...
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Why does a graph of radius vs velocity of an object undergoing circular motion have a quadratic slope? [closed]
I'm doing a project with uniform circular motion and I cannot for the life of me understand the conceptual side of the graphs. On a graph of velocity vs radius of a bob undergoing uniform circular ...
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Can I change $4 \ \text{cm}$ to $4.000 \ \text{cm}$ if I want to divide it by $0.127$ to make it appear in $4$ sig figs?
I need to write a report on angle and length. Can I change, for example, $4 \ \text{cm}$ to $4.0 \ \text{cm}, \ 4.00 \ \text{cm}$ or $4.000 \ \text{cm}$ as I like if I want to make the division sig ...
2
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2
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Noise in gravitational wave detections
I'm reading a paper (https://doi.org/10.1103/PhysRevD.49.2658) in order to understand the use of Fisher Matrix in gravitational wave detection. I'm a bit confused with the assumptions they do about ...
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Optimizing simulation parameters to fit to data
Good day everyone, not sure if its the right place to ask, but any help would be greatly appreciated!
As a quick explanation, I am working on spintronics in epitaxial systems. The usual methods of ...
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235
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How to compare XRD data from literature?
I'm a grad student. Trying to do a literature review this summer. My advisor is telling me to gather XRD data of my samples for my research, and I have. Unfortunately, I have no idea how to compare it/...
2
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132
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How to extract the "matter fluctuation amplitude" from the CMB power spectrum?
How do you convert the value listed in Planck 2018 results. VI. Cosmological parameters, $A_s = 2.101\times10^{-9}$ to the value of the matter fluctuation amplitude $\sigma_8=0.8111$? I tried ...
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What relationship between the time recording length and the frequency bandwidth?
In model testing for ocean waves, the data recording duration is usually longer the better especially for irregular waves. The recording length shall be long enough to achieve sufficiently small ...
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0
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Where can I find spectra data and light curves of a stereoscopic binary star system?
I am trying to find a suitable source of spectra data and/or a light curve of a binary star (no exact star in particular), with which I would use to find velocity and period, and then find masses etc.....
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Does it make sense to whiten the data in order to apply a matched filtering algorithm if my dataset consist of a sinusoid + random Gaussian noise?
With a Python program I generated a sinusoid signal and I added to it Gaussian noise.
Now I want to compute the optimal SNR by applying a matched filtering algorithm.
Since the noise is white (at ...
2
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0
answers
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Interpreting non-normalized covariance matrix eigenvalues as physical Actions
Summary: Eigenvalues of a "non-normalized" covariance matrix of time-series measurements from a linear system have units of Action (energy * time). Can we interpret this to obtain ...
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Spinning gyroscope loses weight?
I ran two tests with a toy gyroscope spinning on a weighing scale that is accurate to $1$mg.
The scale was reset to zero before the tests. The gyroscope was flipped over between test $1$ and test $2$. ...
2
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1
answer
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What experimental data do we have to plug into the Standard Model for it to work?
In the formulation of the Standard Model, I've always been told that we need experimental data to fix some parameters. What are these parameters and how vital is it that we have the exact value? In a ...
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In a uniformly accelerated motion experiment, the acceleration can be attained from $V_{ave}$ vs. $t/2$ and $x$ vs. $t^2$ graph. How is this possible?
Specifically, in the experiment, we had to release a glider from an inclined plane (that had an angle of inclination of 10 degrees). We had to calculate the time it reaches the final position. We had ...
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Can I use the Ph. Eur. definition for signal-to-noise to determine limit of detection for spectroscopic data?
The European Pharmacopoeia defines the signal-to-noise ratio (S/N) as follows:
S/N = 2H/h
Where H is the height of the peak from the baseline and h is the range of the background noise.
Now on to my ...
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How to use error propagation formula in equation with inseparable variables?
$$
R_i(t) =
\frac{\mu_{s,E_i}+\mu_{s,E_0}}{\mu_{s,E_i}-\mu_{s,E_0}}
\cdot
\frac{e^{-\rho\sqrt2\mu_{s,E_0}}-e^{-\rho\sqrt2\mu_{s,E_i}}}{1-e^{-\rho\sqrt2(\mu_{s,E_0}+\mu_{s,E_i})}}.
$$
How do I can find ...
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Observation of the effect of gravity on the motion of antimatter
In a recent paper (https://www.nature.com/articles/s41586-023-06527-1), the authors state that
we find that the local gravitational acceleration of antihydrogen is directed towards the Earth and has ...
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When using the slope or area of a graph to calculate things, do the scales of the units on the axes of a graph need to be the same?
If I want to find the resistance(R) from a voltage(V) vs current(I) graph for a given wire using the relation tan Θ = ΔV/ΔI = R, do the scales on the axes need to be the same, independent of the units?...
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What is the optimal measuring time split for limited measuring time between signal+background and background in a Poisson counting experiment?
I’m trying to figure out the best split of time between measuring either background or signal+background in a counting experiment in the case where we have no prior knowledge about the mean signal ...
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0
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Decomposing circular diffraction patterns
I have the following diffraction pattern produced by a fabry-perot etalon
The red represents the center of that pattern. Taking the mean intensity of the pattern as a function of the radius from the ...
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1
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Binning in histograms
I have a spectrometer which outputs a dataset of Irradiance (Watt per meter² per nanometer) in the vertical axis vs. wavelength (nanometer) in the horizontal axis.
The fact that it is per nanometer ...
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Correlations in the Hellings-Downs curve for the NANOGrav 15-year dataset
I'm trying to reproduce the Figure 1c from the paper "The NANOGrav 15-year Data Set: Evidence for a Gravitational-Wave Background". This graph corresponds to pulsar pair correlations of the ...
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1
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Is this already an established functional relationship or have I created hodgepodge?
Last winter I started toying with the galaxy gravitational rotation curve graphs. I started modifying the exponent of $r$ that in effect change the $1/r^2$ law and therefore correct the mismatch, ...
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Project for Elementary Particle Physics Course
Good day! Are there any publicly available dataset in the field of particle physics that can be treated as time series? I am hoping to use methods in white noise analysis to somehow determine ...
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Signficant figures of calculated values?
Consider the above table. The AS practical examination markscheme states that the signficant figures of calculated values should be the same or one more than the values it was calculated from. We also ...
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Error analysis via two different methods
We have a quantity $a$ expressed in terms of two quantities $b $ and $c$ as $a = b/c$.
It seems to me that there are two ways of estimating the error on $a$, the "physics" ...
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What machine learning technique can help generate spectrum line profiles?
I'm trying to work with Calcium-K line profiles from the Sun.
Image for reference. Please ignore the labels on the image and note that my profiles are not in image format (more info below).
I have ...
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1
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Aggregating an atmospheric gas concentration profile
I have a list of CO2 gas concentrations in the atmosphere in g/g relative to dry air according to a pressure profile. I have the top and bottom pressures for each level.
The list corresponds to a 40 ...
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Line of Best Fit with or Without Constant Term
Some other physics teachers and I were discussing an AP problem about a potential experiment for measuring $g$ and disagreed on the best way to use a line of best fit to analyze the data.
The ...
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521
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Count vs Count-per-channel
Hi there Wise people of the internet,
I am trying to do analysis some data gathered from a gamma scintillator setup, its stored in root.
So i have to do some coincidence measurements, and i found that ...
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1
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0
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94
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How can I optimally rotate accelerometer readings so that the integrated velocity ends up correct? [closed]
I attached an accelerometer (with gyro/magnometer) to a curling rock and threw it down the sheet of ice. The accelerometer was not flat, and it did not travel significantly in the $z$ direction. I ...
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What is the difference between 7TeV and 13.6 TeV ? Why don't we just dump the low energy data and use the one with highest energy?
I saw some results from particle physics that combines 7 TeV and 13.6 TeV results but they are different. Why they are different? Why do we combine them? If we need them why did LHC stopped taking ...
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0
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78
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Damped harmonic motion experiment, bad results but good statistics
I've done an experiment with a pendulum swinging at very small angles. I added an object with the shape of a rectangle to it, to increase the air friction to create damped harmonic motion.
This is the ...
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