# Tagged Questions

Functional Data Analysis defines a framework where the fundamental units of analysis are functions.

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### Forecasting of density function

I am doing some research about forecasting time series of probability density functions. We are aiming to forecast a PDF given historically observed (usually, estimated) PDF. The forecasting method we ...
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### Predicting response from new curves using fda package in R

Basically all I want to do is predict a scalar response using some curves. I've got as far as doing a regression (using fRegress from the fda package) but have no idea how to apply the results to a ...
2k views

### How to simulate functional data?

I'm trying to test various functional data analysis approaches. Ideally, i'd like to test the panel of approaches i have on simulated functional data. I've tried to generate simulated FD using an ...
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### Estimating speed from position updates with uncertain time intervals

I have 2 alternative methods to solve a problem, and I was just wondering what people who know the math better than I think, and if there is a better method to use for this type of problem. The ...
470 views

### How to map a trajectory to a vector?

I have a series of data points in this form (timestamp, lat, long) for a set of users. Each user has a trajectory when he travels from point A to point B. There might be any number of points from A to ...
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### Dynamic Time Warping and normalization

I'm using Dynamic Time Warping to match a "query" and a "template" curve and having reasonable success thus far, but I have some basic questions: I'm assessing a "match" by assessing whether the DTW ...
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### Modelling longitudinal data

We have longitudinal data on children(n<20) in which we measure different quantities A,B,C,D (like distance walked, time spent in school etc.). These are all continuous variables. We measure these ...
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### Confusion about when to use least-squares regression analysis

I am going through an article titled On the misuse of regression in earth science. On page 65, the author say as follows about the least-squares method. It is usual to require that the ...
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### Multinomial Count Models

Is it possible to model a dependent variable which is both multinomial and count? If so, how would one do so with a tool such as R? For example, suppose that my dependent variable looks like this: ...
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### Predicting curve registration parameters in functional data analysis with noisy data

I have some data I'm studying where functional data analysis seems like a promising approach. But having never tackled FDA before, I'm having trouble wrapping my head around it. For background, I ...
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### What is the level of measurement of image data?

Question: This is a bit of an abstract question, but bear with me. I am averaging images, to try and deduce what the average image of a specific subject looks like (just out of curiosity, it might ...
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### Alternate terms, or definition for functional logistic regression

I have recently come upon a paper discussing "functional logistic regression." I could not find literature related to functional logistic regression. Is there a different name for this kind of ...
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### How to consider different samples in functional data clustering?

In the engineering context several data sources like different kinds of measurement signals (for example distances, angles and efficiencies) are very common. If it would be possible to observe these ...
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### What statistics to use when the data are polynomial functions (aka change over time)?

EDIT: OK, having spent the last couple of hours checking out some pubs on functional data analysis, I am actually starting to feel a little silly having asked the question in the first place! It's ...
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### Forecasting ranges for multiple observations with quarterly data

I have 90 markets with quarterly results, with data from 2014 Q1 to 2016 Q2. I'd like to predict 2016 Q4 results. With a time-series in R, as I understand, you need a single observation over multiple ...
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### Data analysis on multiuser environment

I have following environment that I'd like to analyze. My company is divided in two teams: Insert Team (composed by 150 persons) Quality Check Team (composed by 10 persons) Suppose that all ...
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### Different number of time-points in functional data analysis

I have a data set that I wish to analyze using functional data analysis methods. Data consists of repeated measures of some characteristic on a number of inviduals. I have the time of the measurements ...
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### Limiting joint distribution of estimators; Functional Statistics; Influence curves;

Let $X_1,...,X_n$ iid r.v. with distribution F, with mean $\mu$ and median $\theta$.Assume that $Var(X_i)=\sigma^2$ and $F'(\theta)>0$. If $\hat{\mu}_n$ is the sample mean, and $\hat{\theta}_n$ the ...
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### Variability of a curve with 4 parameters

Say I have 10,000 data in 2-D and I want to fit a curve to them. There are many functional forms this curve could take -- polynomial, B-spline, trigonometric, and so on. I've decided that I only want ...
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### Create a function from a data set when there is one independent variable and 3 dependent

I have a data set which consists of 1.Number of users, 2.Cpu usage, 3.Ram Usage, 4.Response time, The way I understand it Number of users is my independent variable. Is there a way, a method, or a ...
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### Estimate global mean and stdev from samples taken at regular intervals

I have data from a load test of an automated system with several thousand data points that cover roughly 1 week of operation. I need to compare several algorithms for this system to see which is ...
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### Canonical Correlation Analysis in R

I have a dataset of temperature readings of different burner parts which determine the final temperature of the burner and time to set off burner So my dataset looks like this: ...
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### Question about example in Linear Models for Functional Responses

I am reading Chapter 10 Linear Models for Functional Responses of Functional Data Analysis with R and Matlab by Ramsay. On page 148, the book mentions the model for "Climate Region Effects on ...
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### How to show whether a hypothesis is true or not

I have the following hypothesis: "The higher the number of translation-stable words between a pair of countries, the higher the correlation between the happiness scores of their words". note: ...
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### Find out whether the answer to a question depends on a group

I've distributed a questionnaire to four different groups of people. An example of a question in the questionnaire is: Do you want to be informed about financial topics through social media? Yes/no. ...
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### Longitudinal data using functional principal components mixed effect models

I have collected speech perception performance in children during one-year followed-up (four time points). A battery of speech perception measures (i.e., five measures) were used at each test interval....
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### Can I validate results after statistical hypothesis testing?

I have data from one clinical test for 450 patients. Depending upon my objective, I divided data into 7 different categories to compare two groups, in each category (inherited from parents and not ...
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### How to select the optimal number principal components in functional principal components analysis?

I am interested in the selecting the optimal number of principal components in functional principal component analysis (FPCA). There are various techniques to do that for example AIC, BIC etc. (I am ...
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### Functional regression with two predictors, one of which is an angle

I'm designing a machine, and I want to investigate the effect on performance of 2 predictors, a length $l$ and an angle $\phi$. Performance is defined by two response curves $y=f(x)$ and $z=g(x)$: ...
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### How to select the number of basis functions and smoothing parameter in functional data analysis?

I am confused over the selection of number of basis and smoothing parameter for particular data set in functional data analysis. I have two data sets (A) Daily temperature data set of England of 228 ...
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### confirmation and validation of a lab environment versus real life scenario

I'm having some trouble trending turbofan jet engines exhaust gas temperatures (EGT). Data collected shown that EGT measured in the test cell versus EGT measured on-wing while flying is different. ...
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### Comparison between the coefficients of two GLMs

I would be happy to have your thoughts on the issue of comparing the beta-values resulting from two different GLMs. Should the beta values be scaled before a statistical comparison? which test would ...
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### Setting a Target or Benchmark based on Historic Process data

We have 15 Work processes for a departments. There is the historic data for the dept with all the information. Data defines the which process is done by whom, minutes of work, start date and finish ...
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### Is Multiple Regression the right choice for my statistical design?

I am studying the relationship between mental health offices and judgments of perceived care expected within those environments. Participants will rate different photographs of mental health offices (...
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### Problems about B-spline estimation method

When I took non-parametric regression course, I was required to fit the regression of log-pollen over the course of study (day) with the kernel density estimation method. Since my instructor also ...
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### Alternatives to absolute error?

Let me explain my scenario in which I need to calculate absolute error. Lets say the X is the actual value. And X' is the value of X with some error 'e'. So X' = X + e'. Lets say i = 1 to 10000. I ...