Questions on the use of Mathematica to construct models for approximating empirical data.

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0
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0answers
28 views

choosing the number of points in FindFit function [on hold]

I am trying to find the best function to fit a set of data as following, ...
5
votes
1answer
107 views

How are p-values in fittings estimated?

I am trying to understand how p-values retrieved in a ParameterTable estimated but I couldn't find any specific information in the documentation about this. For instance, considering ...
0
votes
1answer
78 views

Binomial Regression where n > 1

I am not well versed in Generalized Linear Models, but am trying to use this approach to model some discrete data. I have binomial data where the sample size for each observation is the same size, ...
1
vote
0answers
66 views

NonlinearModelFit::nrnum error [on hold]

I'm trying to fit data (including some small negative numbers at both extremes) to a normal distribution. ...
-1
votes
1answer
55 views

Pulling variable out of NonlinearModelFit [on hold]

I have a fit, Dynamic[f1 = NonlinearModelFit[d1, a Exp[-(b (x - c1))^2] + yoff, {a, b}, x]] Where I need to be able to access ...
5
votes
1answer
76 views

FindFormula can't deal with the population data from Wolfram server

In the documentation of FindFormula, the first application of it is to predict the population of Poland. ...
3
votes
2answers
77 views

Gauss Fit to List of 2D Points

I've been trying to find a solution to what I think is a common problem. I have a list of Data like ...
27
votes
2answers
439 views

What is behind Mathematica's experimental `FindFormula` function?

In version 10.2 there is a new experimental function: FindFormula. I suspect that a genetic programming algorithm (symbolic regression) is behind this new feature ...
13
votes
4answers
1k views

Implementation of smoothing splines function

I have some problems in writing a module for spline smoothing. Actually, I have been trying for about two weeks. My listing is here: ...
-1
votes
0answers
18 views

How to fit a 3-parameter logistic model by R and GLM [closed]

I have a model follow a 3-parameter logistic model like: $E(Y|x;\beta)=\frac{\beta_2}{1+exp\{(\beta_1-log_2x)/\beta_0\}}$ How can I use GLM to fit this model in R?
0
votes
0answers
51 views

Modify measured values to improve NonlinearModelFit results

Problem: Measured data points have a random distribution of DC offsets (either +/- 0.65 mV), that came from an incorrect setting on the 24-bit ADC we were using. Essentially for each measured voltage ...
2
votes
0answers
96 views

Fitting local regression through data

Is there a way to fit local regression through data in Mathematica (equivalent to say "smooth" in ggplot-R)? I've literally spent the last hour searching the internet and documentation centre and I ...
1
vote
1answer
88 views

Problem fitting when some data is missing

I have a problem fitting a function to data, where I only have the falling and rising edges of the data, with the peak having been capped and was wondering if you have some tips. The data should have ...
3
votes
1answer
139 views

NonlinearModelFit: fit a vector-valued function to a data vector

I have a vector of data points: data = 10 Sin[#/10] + RandomVariate@NormalDistribution[] & /@ Range[200]; And I have model that provides the complete ...
6
votes
3answers
2k views

Find a best fitting curve for some data with no regular pattern

Suppose some data with no regular pattern is given, so common patterns of functions all fail to fit it. Then how can one find the best fitting curve? I believe there will be some data for which we can ...
16
votes
2answers
569 views

Curve fitting by running through hundreds of models and return the one with best fit

In the past, I used to solve a lot of my regression analysis (curve fitting) problems with a program called DataFit which runs on Windows. It has hundreds of regression models which it runs through in ...
0
votes
0answers
54 views

How to calculate the standard error of a parameter for a simple nonlinear fit?

I am trying to get the standard error of the estimate of a parameter in a simple nonlinear fit. I manage to get it for a linear fit. I used the formulation from a previous post. Here is my code for ...
3
votes
0answers
83 views
0
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0answers
3 views

Heston Model parameter estimation [migrated]

I would like to know, whether there is some literature or paper (even better) available that examines the Heston model parameter estimation. I am not searching for calibration, it should only focus ...
2
votes
3answers
170 views

Fitting and plotting Weibull distribution

How can I find the best fitted 2-parameter Weibull's distribution (PDF) to describe my data? How can i plot my data and estimated distribution all in one graph? How can I show/compare results of ...
2
votes
1answer
72 views

Still more problems with Fitting, please help

I'm in a little over my head here and I'm fully aware of it, so I'm hoping for some help. I've been assigned to a project where I am given data: http://www.pastebin.ca/3061136 (Example Data) I ...
1
vote
1answer
95 views

non linear Least Squares with model function given by ODE's

I have to fit to experimental data a model function given by a linear combination of functions y1(t) and y2(t) a1*y1(t) + a2*y2(t) with a1 and a2 ...
2
votes
2answers
55 views

Using FindFit for a non-trivial complex function [duplicate]

I have data set which I would like to fit to the function $\quad \quad f(r) = A\cos(kr - \pi/4 + \phi_1)\times\exp(i(-2\log(r) + \phi_2))$, where $k$ is a constant I know and $(A,\phi_1,\phi_2)$ are ...
2
votes
1answer
66 views

LogitModelFit bias term when using design matrix

I'm using the LogitModelFit function with a 32-columns design matrix and 0 or 1 output vector: LogitModelFit[{datax, datay}]. ...
2
votes
2answers
58 views

Fit model with two dependent variables

Say I have an experiment that produces two values, for a given input. For example you get a complex response value. Now I have a model that - of course - also produces two dependent values for one ...
1
vote
2answers
87 views

TargetFunctions option in FindDistribution yields error

I have some data set that I am trying to find the maximums . I figured I could do this by fitting the many peaks of the dataset to Gaussian distributions and then finding the peaks of this data from ...
1
vote
1answer
66 views

Curve fitting data I imported from excel [closed]

This is my first time posting here, so sorry if I break any rules. There is this excel document from which I imported two columns of data to mathematica. I need to fit the data into a curve so that ...
0
votes
1answer
40 views

Mapping Linear Model Fit Over An Arbitrary Number of sets

I have multiple sets of data, and I want to apply Linear Model Fit sequentially to each set of data. For example, below tstlst contains 3 data sets. Right now I ...
13
votes
6answers
11k views

How to determine the center and radius of a circle given some points in 3D?

I was wondering if anyone could give me a hand with this problem I have. I have six points on a plane, and I am trying to determine if they form a circle or not. I know that any three points in 2D ...
3
votes
3answers
272 views

Fitting - Exponential

I'm trying to fit the following data using Mathematica, but unfortunately im not getting any decent results. ...
1
vote
0answers
85 views

Solution to heat equation with Neumann boundary conditions and lateral heat loss

I am conducting an experiment on heat conduction in a copper rod. To do so I am using a thin copper rod with several temperature probes, then I am going to compare the data with a solution to the heat ...
4
votes
1answer
153 views

Find a Fourier series from discrete data

I am trying to fit a Fourier cosine series to discrete data. I read through this, but I was not able to understand it. This data should be periodic with a period of $0.2 \textrm{m}$ and it is the ...
-1
votes
1answer
80 views

NonlinearModelFit errors and precision

For this problem, I use a data set, which I've made available here. ...
0
votes
0answers
32 views

R^2 values for piecewise regression

So I've used NonlinearModelFit on a Piecewise function and gotten a nice little piecewise regression. This is what my code looks like: ...
1
vote
2answers
77 views

Non Linear Model Fit (Division by Zero Error Message)

Can someone please tell me why this expression returns error messages about division by zero. ...
1
vote
2answers
65 views

What is the role of the pattern object in this implementation?

In the documentation I found a nice idiom which allows me to do model fitting with interpolating functions. I think this kind of thing is amazing and a credit to the utility of an environment like ...
0
votes
0answers
26 views

Fitting problem: InterpolatingFunction can not be localised

I got simple data looking as follows {{541.447, 311752.}, {540.359, 311723.},.. I tried to fit it in mathematica for the first time with a function that usually ...
0
votes
0answers
34 views

Which one will gives best fitting result?

I want to find out the parameters A, B, and C of the ...
2
votes
1answer
87 views

P-Values are inconsistent when using DistributionFitTest repeatedly

I am attempting to become more familiar with the DistributionFitTest, specifically the distributions it yields and their fittedness. What I have found is that when I generate random data, fit it, and ...
5
votes
1answer
129 views

What does LinearModelFit depend on except for its arguments?

I thought this would be always true, but most likely it returns false. ...
4
votes
1answer
92 views

Substituting ParametricNDSolve for NDSolve

This is my first post so let me know if I need to format things differently. I have been using NDSolve for most problems which optimize parameters for ODEs. I believe that ParametricNDSolve would be ...
0
votes
0answers
54 views

Finding values of a variable fitting a function and minimizing a list of expressions

I am trying to implement bootstrapping (https://en.wikipedia.org/wiki/Bootstrapping_(finance)) of CDS curve. To implement it I am trying to minimize a series of expressions so that each expression is ...
1
vote
1answer
85 views

Plotting data after fitting it to exponential function [closed]

I am trying to plot h vs t such that h fits a equation ...
4
votes
1answer
1k views

How does Mathematica estimate error on fit parameters?

When performing a fit using NonlinearModelFit (or any of Mathematica fitting functions, but I am particularly interested in nonlinear models), Mathematica makes a ...
9
votes
1answer
739 views

How does Mma compute Confidence Intervals?

I am trying to understand how Mma computes the Confidence Intervals after a NonlinearModelFit. Consider the following example: ...
3
votes
0answers
111 views

Fitting data to a complicated function

So, where to begin. I have a certain dataset that I want to fit to a function. However, the function is rather complicated (matrix inversions, linearsolve) and does in general not have a closed form ...
1
vote
1answer
214 views

Fitting data to a circle with FindFit

I'm currently trying to use the Mathematica's FindFit command to fit a curve of some data to the bottom half of a circle. The data is of the form ...
2
votes
1answer
97 views

Precision of LinearModelFit with Polynomials

I have a Problem regarding the fit of given points with a polynomial up to the fifth degree. tableofvalues=Import["tableofvalues.csv"] My polynomial is: ...