Questions tagged [data-analysis]

Use for question relating the the techniques of data analysis.

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How to check the particle rate of $1\ m^{-2}.s^{-1}$ at an energy of $10^{12}\ TeV$ from the “Swordy plot”? [duplicate]

On this web page, we see the so-called "swordy plot" https://www.quantamagazine.org/ultrahigh-energy-cosmic-rays-traced-to-hotspot-20150514/ At an energy of $10^{12}\ eV=1\ TeV$, we read ...
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18 views

How to calculate uncertainty of rounded data

I have been seriously confused with the following text for a short while. Suppose that three teachers have timed the school 100 m sprint race and have recorded times of 12.3, 12.5, and 12.6 s for the ...
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When linearizing a data point of an inverse relationship, how does its uncertainty change?

I have a question regarding data analysis and uncertainties regarding my physics experiment. Essentially, I conducted an experiment to determine the relationship between salt concentration and ...
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Why is this fraction equal to 1? [migrated]

I am trying to derive the error for the weighted arithmetic mean $$ \langle A \rangle=\frac{\sum_{i=1}^N \frac{A_i}{\sigma_{A_i}^2}}{\sum_{i=1}^N \frac{1}{\sigma_{A_i}^2}}. $$ of a Data-Set $A_i$ with ...
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How to evaluate the parallax error in the measure of diffraction rings' diameter?

I have to estimate with an image analysis the diameter of the rings generated by the diffraction of an electron beam with a polycrystalline graphite target. The pattern is made visible by a ...
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58 views

Millikan oil drop experiment

I had a question about the Millikan Oil drop experiment. I did the experiment for my physics class where we had to determine the voltage that would make the droplet stationary. We did this ten times, ...
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1answer
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Determining the error in gradient through least fit of data

I am try to measure the error in the slope of the black dots. To do this I performed a linear regression to the data using from scipy.optimize import curve_fit on ...
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2answers
50 views

How to work out with how many sigma confidence my measurement confirms the theory?

Suppose by a theory a certain value should be 1. I make an experiment in which I measure it to be 1.1 ± 0.2, where the ± 0.2 are 1 sigma Gaussian errors? Obviously I can see that the theoretical value ...
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How to compare several experimental measurements and their uncertainties?

I have a basic question about how to make the comparison of different measurements. For example, suppose I have measured the focal length of a convergent lens using three different methods, $A$ and $B$...
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51 views

Uncertainty of polar Coordinates

I am trying to do some error propagation to find the error on polar coordinates starting with cartesian coordinates. Using the equations found in Hughes and Hase, "Measurements and their ...
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Model parameter derivation, least squares fitting vs solving systems of equations

PS: Let me preface this with I barely have an idea how to ask this question so bare with my ramblings. I'm trying to fit a 5 parameter model to gravitational lenses. For this I have 2 classes of ...
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How to calculate the Likelihood function of a gaussian pdf

Suppose a model for a flux of (astro)particles $\dot \Phi(E,t)$ (from a supernovae) that depends on particle energy $E$ and time $t$ (from beginning of explosion), and 3 free parameters $T_a, M_a, \...
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Mean of gradients or gradient of mean points

I have 5 repeat measurements of a dependent variable for each of 5 values of an independent variable. To find the gradient and estimate its error, is it better to plot the 5 mean points and find the ...
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What do I set for the standard deviation of a measurement, if the value is not normally distributed?

I took multiple $B$ measurements for a constant $A$ value, which I simultaneously measured. $A$ (in my case the resistance of a temperature sensor) was controlled by a PID controlled and slowly ...
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FFT on a signal with a length that is not a multiple of the period of its harmonics

I was very surprised to find an apparent limitation to a FFT on a simple signal. Let's consider a timeseries made of L=100 points, and simply composed of the sum of two sinus waves: one with a ...
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How can I cluster infrared spectra?

This is sorta a cross-post from my post in StackOverflow. Although, rather than seeking help with the code I'm here asking for help with a physical/mathematical/statistical problem associated with the ...
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What is the difference between horizontal units and horizontal scale at an oscilloscope?

This is a picture of the data of a given measurement by an oscilloscope. I would like to know what the difference between horizontal units and horizontal scale at an oscilloscope is. I would be so so ...
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Why do I have to draw a big triangle to determine the gradient of a straight line using the slope triangle method?

I'm an igsce student, I'm taking igsce OL phyiscs. It's stated in my book that after I draw a graph and the line of best fit, I should get the gradient by choosing two points then form a right angel ...
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Magnetic flux as a function of distance experiment

For my electrical engineering senior design I created an experiment to test magnetic flux (more voltage) increase from a material in a coil of wire. There is a large sending coil with A.C. voltage and ...
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Does it make sense to average data taken continuously as the system evolved?

I have a simulation where a bunch of particles are moving. Every time step I fit a gaussian (through non-linear least squares) to the distribution of speeds. Here I end up with a temperature $T_i$ and ...
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What is the relation between statistical and instrumental uncertainty?

I've been studying some error analysis on An Introduction to Error Analysis: The Study of Uncertainties in Physical Measurements by John R. Taylor for an introductory course. At the beginning of ...
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Q. Significant figures on graphs

When displaying experimental data on a graph, must both axes use the same number of significant figures, which would be the variable with the smallest number of significant figures? Or (because a ...
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X-Ray Diffraction pattern peak tailing

I have recently been working with Rietiveld refinement on powder X-Ray Diffraction (XRD) patterns by using the GSAS2 (General Structure Analysis System) program where, one of the steps, is to produce ...
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Calculating the distance between a nuclear bomb and an object hit by the shockwave, all the while taking the video frame rate into account? [closed]

Imagine you are watching a YouTube video where a nuclear bomb goes off. Exactly six seconds later, the shockwave arrives and hits an object that is some distance away. How would you go about ...
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Prevent biased data analysis

When analysing experimental data it is simple to fool oneself. Therefore, I am interested in methods to prevent myself to draw biased conclusions. Robert MacCoun and Saul Perlmutter: "Blind ...
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What’s the difference between ‘decimated‘ and ‘undecimated’ data?

How is ‘decimated’ data different from ‘undecimated’ data?
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Linear fit error for beta decay spectrum

I'm trying to get an upper bound to the neutrino mass with kurie plot. In order to do that I need to make a linear fit in order to get energy value that corresponds to $y=0$. ($y$ the kurie plot). The ...
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What is significant in broad and narrow resonance peak to internal structure of the resonance?

I read about the multiquark system and It seems like many people said that a narrow peak mostly likely to be a molecule structure. The broad peak seems to be a compact structure. This is like a kind ...
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Generating Positive Kinetic Energy (PKE) from car velocity [closed]

PKE have high importance on fuel consummation and Eco-driving. I have a data frame with 3 columns, Time (each second), Speed(KM/H) in each second, and RPM ,from this data frame I want to calculate ...
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Understanding the ordinate at $R=0$ in a capacitor experiment [closed]

I've done an experiment to study a capacitor's discharge time and calculate an unknown capacitor's capacitance. With the help of an oscilloscope, I measured the time it took for the capacitor's ...
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I don't understand how to interpret “Events/MeV” in plots like this

I was reading a paper regarding electron excess events in MiniBooNE data and I came across the following plot: I don't understand how to interpret the meaning of "events/MeV". This is a histogram and ...
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Modelling a spring powered car - using a cubic

I've designed, built and tested a mousetrap-powered car. However, I'm having trouble with how to fit the results. I claim an approximate fit to a displacement-time graph of the car should be a cubic ...
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How to incorporate the uncertainty of the model coefficients in the prediction interval of a multiple linear regression

I'm dealing with the modeling of small experimental physics data sets (specifically the stickiness of glue-compounds). As most experimental work does not generate thousands of samples, but rather a ...
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Optimizing Muon Lifetime Data

I performed an experiment which measured the lifetime of a muon. The apparatus was very archaic and susceptible to disturbances, which means that there would inevitably be some unreasonable data ...
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Power Spectrum Density of real valued time series data

There are real valued time-series data X(t) and corresponding auto-correlation function ACF(t)=$\left<X(0)X(t)\right>$. As written in wikipedia, Power Spectrum Density (PSD) can be calculated ...
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Optical pyrometry data analysis and manipulation

Today I was doing my Optical pyrometry lab experiment with a following setup. I had a wolfram wire light bulb connected to a circuit in which I could control voltage. Using the pyrometer, I was to ...
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Homework/Lab question about my data analysis

I in the experiment, I have tried to find a relationship between a quantity B and quantity I. First I plotted the raw data into a graph and tried different curve fits in excel. This is the graph that ...
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Graph analysis of accelerometer data

I used my mobile accelerometer sensor to collect data from a moving bike where I held it in my hand in a way that the smartphone sensor +Y axis is in the direction of the moving bike always. This can ...
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Can we plot a FFT for a Decibel vs Seconds data?

I was plotting FFT for Decibel values corresponding to the time in which it was recorded using a DAQ for My project, The sample data looks like this, I was attempting to plot the FFT thinking that ...
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484 views

Light Bulb Resistance

If the voltage and current of a circuit containing a light bulb are measured using a multimeter after consecutively lowering the voltage (building of a data set), what (type of) function will describe ...
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How long should I record the data of walking acceleration for FFT analysis?

Seems there is no apparent frequency of walking activity (it should be approximately close to 2 Hz) Is it because the time of the data is too short? Here is my csv file:enter link description here
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How to subtract background from many spectra which were taken with different background intensity?

I have two spectra, a spectrum of background signal (let's call it Reference) and measured spectrum consisting of searched signal and background signal. The searched signal is a peak/s with various ...
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51 views

Calculating uncertainty in a fitted model

I am working on a project that requires the measurement of the Verdet constant of a material by observing a phase shift in the cosine squared model provided by Malus's law. I have recorded the ...
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How to combine several dependent predictions and get the best estimate?

I want to predict the value of some physical quantity $P$ at a time $t$ using actual measurements of $P$ acquired before and after $t$. The formula I use for making these predictions is: $$\hat{P}_{t}...
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Question about FFT analysis of a signal

In labs we had to measure the oscillations of a pendulum using an electric sensor. So basically, my data consists of time and voltage (which represents amplitude) pairs. The task was then to perform ...
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How exactly do you avoid fooling yourself?

In cargo cult science Feynman writes: "Millikan measured the charge on an electron by an experiment with falling oil drops, and got an answer which we now know not to be quite right. It's a ...
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Linear Regressions vs Algebra & Averaging in Solving for a Constant

I'm current taking AP Physics, and in both of the labs performed so far (Snell's Law/Refraction and Galileo's Inclined Plane), I have been trying to calculate some constant from a linear relationship ...
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Step-like contribution to background $\gamma$ ray peaks

I'm reading the paper "Analytical functions for fitting peaks from Ge semiconductor detectors" by R.G. Helmer and M.A. Lee. For $\gamma$ ray peaks the spectral "background" in the region of a peak: ...
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What physical interpretation can we derive from this experimental step up?

(This is not a homework question!) An experimental set up shows 2 rigidly placed stands, with pieces of metal links joining with each other forming a chain. The chain is hung from the top point to ...
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Is there an index of common spectral lineshapes or table of common lineshape functions?

Is there an index of common spectral lineshapes in physics? Is there a program that automatically tries fitting to many different lineshapes? By line shape I mean the function that, given ...

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