Questions tagged [curves]

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Cox regression curves or Kaplan Meier?

Why not just present the survival curves from Cox cox survival regression analysis instead of Kaplan Meier curves?
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61 views

In order to leverage a cox model for calculating adjusted survival curve - one must estimate the baseline hazard function. To my understanding this has to be estimated (non parametrically) for ...
1 vote
24 views

How to start GNN optimization to get higher precision?

I'm developing a GNN for missing links prediction following this blog post for PyG library. I'm using almost the same GNN with a different dataset. Altough my dataset is similar to the MovieLens ...
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1 vote
20 views

Can comparison between curves be achieved statistically to group into similar and different sets?

I have a set of aggregate grade data and want to know if it is possible to determine if there are groups of samples of similar grade fraction using R studio. Some of the data: Column A contains ...
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1 vote
60 views

Phonological errors in children

I have a data (ge3_ratio) with 86 observations measuring the ratio of phonological errors produced by children. The data was collected from spontaneous speech transcripts from 3 children aged 21 to 65 ...
• 11
871 views

cmprsk cumulative incidence - comparing between two curve with different outomes

I have a question regarding the extracting p-values from the cumulative incidence curves that considered competing risks. I used cmprsk packages and ...
• 31
2k views

Log-rank test for comparing three survival curves?

I have a plot of three survival curves that are stratified by a categorical variable (a=1,2,or 3). The log-rank test can be used to test the global null hypothesis that all these curves are the same, ...
81 views

Curve quantification

I have some longitudinal measurement data of 15,000. I smoothed that data with B-spline smoothing and got the following curve. I then want to quantify this curve and extract features for clustering ...
28 views

Power demand Curves

Which is the correct way to compute the elasticity in this log log regression? Context: When having an log log regresion: log(Y) = log(B0) + B1 log(X), being Y= Demand and X Price, B0 intercept and B1 ...
• 75
840 views

Statistical difference between curves

I have 12 curves (three replicates for each treatment), see attached picture. X=days; Y=percentage. The experiment has 2 variables: A: 4 cases; B: 3 cases. I would like to know, if there is a method ...
1 vote
331 views

Best Loss Function for Shape Resemblance in Time Series

Basically, predicting future values step by step using past values and some covariates as a feature, using some LSTM, Conv layers from tensorflow. I started by using mean absolute percentage error as ...
• 553
477 views

why does log scale does not start at 0

I need help in understanding the curve shown in the image. As you can see in the image that I-V curves in (a) is for linear scale and it shows 0 Amps at 0 Volts. But for logarithm scale I-V curves in (...
1 vote
226 views

Representation of population data mean/median (similar to BMI/age curve)

I want to represent my data (n=150 samples with a curve of value over time, similar to BMI representations in figure). Possibilities are either mean/std and median/percentiles. The question are: Can ...
1 vote
3k views

How to fit the flipped exponential-function in Excel? [closed]

I would like to know whether it is possible to fit the second graph below in Excel with an exponential fit? Unfortunately the "Exponential fit"-button is greyed out and I can't choose this ...
195 views

Intuition behind Cumulative Accuracy Profile(CAP)

I am really having trouble understanding the intuition behind Cumulative Accuracy Profile(CAP) Curve. I mean where exactly does the CAP curve is used and how do you read the CAP curve? Parts of the ...
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modeling a electrical pulse which is technically time dependent

I have an electrical pulse that I need to fit a curve to a certain area of but not the entire thing. The whole pulse looks like this However the only part that I need to model is this My boss ...
981 views

I've been asked by a reviewer to plot an adjusted Kaplan Meier graph. I understood that with sts graph and adjustfor, the adjustment was to zero values of all the variables. So I tried to use stcurve,...
1 vote
626 views

KS-style test between curves in general

The setup of my problem is that I have some response variable, $Y$, and a predictor, $X$. I have measurements on both variables from two groups. In each group, there is one $Y$ per $X$. I want to ...
• 65.1k
184 views

Standardize by min, max, and arbitrary chosen middle to range from -1 through 0 in the middle to +1 in max

How to standardize data by the following example: ...
• 1,188
1 vote
72 views

Difference/comparison of two different sized sets of data

I have the data of two different devices (a and b) measuring the same outcome along the time. These results are approximate but have different values. I would like to assess the variation/agreement ...
575 views

In elbow curve how to find the point from where the curve starts to rise? [closed]

I am computing a distance on my data. The result is then being sorted in ascending order. The samples having distance more than a specific threshold are to be marked as outliers and will be discarded. ...
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1 vote
326 views

Should Learning Curves be Plotted only on Train or the Entire Dataset?

In order to compare a few models to start my ML project, first I split the dataset into train and test, and then performed nested CV on the training set only and got my fair estimate of true risk on ...
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1k views

What defines a plateau in a saturation curve?

I am working on a dynamic visual. To be more specific, it is a saturation curve (also known as accumulative/cumulative curve that reaches to a maximum of 100%. I am trying to define a variable that ...
1 vote
98 views

What method can I use to produce a single curve from a number of curves?

I am looking for a good method to combine a set of curves into a single curve. Those curves have been produced by performing a measurement/testing n-number of times under similar conditions. What I ...
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256 views

how to calculate curvature of multivariate function?

EDIT1: tried to clarify the question Context In the context of an MCMC investigation of non-linear interaction effects in dichotomous models, I am creating data generating processes based on the ...
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1 vote
52 views

How to represent local significant differences between curves

I want to compare some curves to a 'normality corridor', and I would like to show in what regions (x values) the difference is significant.Take the example below, where I want to compare the dashed ...
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137 views

How to compare curves behavior?

I want to know how I can compare the "behavior of curves" and see what curves behave more similar. In the link below, in the 1st graph we have 4 curves through out time. http://www.sooty.ca/sooty/BDI....
2k views

ROC curve:difference between FPR x TPR and false positives x true positives

Background I'm trying to understand ROC curves, however I sometimes read that you can simply go one up for a True positive (TP) and one to the right for a False positive (FP), as mentioned here: ...
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ROC curve: small focused sample vs large sample

Background I'm currently reading the book Data ming: practical machine learning tools and techniques and came across the following ROC curve: The text corresponding to this figure: Method A ...
• 753
635 views

Choosing estimator based on Precision-Recall Curve

I hope you will help with this one. Below you see my Precision-Recall curves after performing 10-fold Stratified Cross Validation on my dataset. Note that my dataset is imbalanced that's why I'm ...
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1 vote
1k views

"Changing" standard deviation?

I will admit to being just a hair about a novice when it comes to stats, but I feel like I have a decent working knowledge of things such as normal distribution, linear curves, standard deviations, ...
1k views

How can Precision-Recall (PR) curves be used to judge overall classifier performance when Precision and Recall are class based metrics?

How can Precision-Recall (PR) curves be used to judge overall classifier performance when Precision and Recall are class based metrics? Since in a binary classifier, there are two classes, often ...
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269 views

Logistic-regression probability score used for reordering rows for plotting ROC curve: is it the actual, positive, or negative class probability?

I want to draw my own ROC curve, such as explained in the accepted answer to this question: Understanding ROC curve However, it isn't clearly explained what the 'score' used represents. It is used ...
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1 vote
3k views

ROC AUC and PR AUC: Are the AUC values different for each class?

When dealing with a binary classification problem, where the decision function threshold is being varied from 0 to 1 at step 0.1: When calculating the Area Under the Curve (AUC) for a ROC Curve plot (...
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129 views

Normal distribution curve percentages

Lets assume I’m grading following a normal distribution but instead of having a standard grading scale from A to F I have a grading scale from A to J with no plus or minus. Whats the percentage for ...
1 vote
212 views

Vertically translated depreciation curve: Update the exponential regression coefficient

I have an exponential regression equation that I use to predict the condition of roads. The equation can be found on page 53 of the original master's thesis: Development of a Flexible Framework for ...
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1 vote
2k views

How to extend the dynamic time warping to 3D Cartesian space

I already searched the topics here but couldn't figure out clearly what to do so I'm asking here. I have thousands of fiber tracts (the outputs of a tractography algorithm on brain diffusion MRI) that ...
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3k views

Exponential regression trendline does not match data

I'm attempting to generate an exponential regression equation using Excel 2010. I plan to use the equation to predict the future condition of roads. I've mocked up a simple chart in Excel using the ...
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418 views

Clustering curves [closed]

I am trying to cluster gas wells based on their production behavior based on Gas/Water ratio vs cumulative water produced plots. Would appreciate suggestions to solve this problem.
1 vote
135 views

Road condition: Project future condition by appending part of a deterioration curve?

I inspect a road network's condition every three years: ...
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1 vote
31 views

Constant Curve for Cumulative Binomial

I am simulating traffic flow and have come across a rather interesting statistics problem that I'm having trouble wrapping my head around. I am modeling a stretch of road comprised of 2 lanes. Lets ...
1 vote
224 views

Curve disaggregation with neural network

I have to extract a specific curve from an aggregate curve. An example is illustrated in the picture below, the blue curve is the aggregate curve, and I want to extract the red curve from the latter. ...
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1 vote
192 views

Statistical test to use to compare EMG waveforms with only the mean and sd?

I have to compare processed EMG waveforms (smooth curves) that I recorded from 7 different leg muscles of 4 different subjects to reference EMG data (Winter book). The problem is that for the ...
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265 views

Comparing two (or more) curves

I'm rather new to R and statistics. I'm analyzing intonation curves (time, fundamental frequency), and I'm interested in comparing pitch curves of different speakers. I am particularly interested in ...
743 views

Getting ROC curve from markov chain in r

I've been working on some attribution modeling in R, following the markov chain-based methodology described here. In order to compare the sensitivity and specificity trade-offs of using models of ...
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4k views

The issue of quantile curves crossing each other

While trying to perform some quantile regressions on some data I have encountered a classic problem: the 0.25,0.50, 0.75, 0.95 quantile curves are crossing each other (I am dealing with linear curves)....
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1 vote
132 views

Measuring magnitude of variation between 2 one-phase association exponential curves

I am currently testing the independence of two unpaired conditions A and B; with each condition representing a set of 12 values (aka bins) that compose a one-phase association exponential curve. Each ...
147 views

Does it take progressively fewer EXTRA correct answers to move up a grading curve in standardised exams?

A previous year's grading curve for an exam I will be sitting is : Assuming the exam has 100 (or any number of) questions each equally weighted, will it take fewer extra correct answers to move up ...
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