# Questions tagged [curves]

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### 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
53 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 ...
35 views

### How to match a curve/image to part of another curve/image?

I have a long curve and want to extract segments with specific feature, the feature is given by a template curve. I intend to use similarity measures like Fréchet distance or dynamic time warping to ...
8 views

### Gains curve and sensitivity

According to this source we can construct Gains curve using sensitivity (putting it on y-axis). As far as I know the sensitivity doesn't have to be equal to 1, but the right-most point on Gains curve ...
1 vote
579 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 ...
70 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 ...
27 views

### 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 ...
530 views

### Adjusted Kaplan Meier in STATA : stcurve or sts graph adjustfor

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
314 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 ...
103 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 vote
66 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 ...
440 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. ...
1 vote
105 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 ...
562 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
84 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 ...
142 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 ...
1 vote
40 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 ...
88 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....
1k 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: ...
462 views

### 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 ...
580 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 ...
1k views

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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, ...
984 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 ...
258 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 ...
1 vote
2k 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 (...
77 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
199 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 ...
1 vote
1k 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 ...
2k 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 ...
311 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
127 views

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

I inspect a road network's condition every three years: ...
1 vote
29 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
216 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. ...
1 vote
179 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 ...
232 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 ...
638 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 ...
3k 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)....
1 vote
112 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 ...
100 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 ...
1k views

### How to measure if data conforms to logarithmic curve

I am collecting data that should closely resembles a logarithmic curve. I have many datasets. How can I measure how closely each dataset resembles a logarithmic curve and call out any outlying ...
36 views

### Extracting values from a sigmoidal dose curve

I need to extract the real lethal doses from a sigmoidal dose curve from a probit model. The doses (mg) are the X-Axis and were log transformed. Model parameters were not reported, only that the true ...
940 views

### Average curve from set of curves

I have done some initial analyses on some patient datasets regarding neuro-degenerative diseases. A method I've used is DFA (Detrended Fluctuation Analysis) in MATLAB, which produced a family of ...
2k views

### Why is the "training score" I get from the learning curve of Multinomial Naive Bayes so different from the training score of the Bernoulli version?

I'm comparing the learning curves of Bernoulli and Multinomial Naive Bayes using the 20_newsgroups dataset from scikit-learn for text-classification. I considered both the "training score" and the "...
1 vote
288 views

### Describe a curve by other than formula, fitting or interpolation

I have a curve defined by a set of $(x,y)$ given points. After ploting these points I get : My aim is to study the sensitivity of the operation that results these points. In order to do that, the ...
39 views

### Name of type of curve that uses x value as a divisor for y

What is (or is there) a name of a curve that is on X and Y axis, where the Y value is divided by X? For example, Y at X being 1 = 100, Y at 2 = 100/2 Y at 3 = 100/3. The type of curve I am thinking ...
16k views

### In statistical terminology, what is the opposite of "peak"?

When we see a curve (or a normal distribution), we describe the highest value as "peak". Let's imagine we have a curve with only a minimum value (like an inverted hat), what do we call that minimum ...
933 views

### Fitting the differences between two curves [closed]

The problem I'm trying to solve is to algorithmically figure out whether two curves converge or diverge in a graph (visually the problem is almost trivial). For examples: The left one is convergence, ...
1 vote