Questions on the use of mathematical techniques to extract properties from given data. Consider if your question might be more suited for Cross Validated (stats.SE) instead.

learn more… | top users | synonyms

1
vote
2answers
227 views

Mean and Median Calculations

A group of 20 has a mean = 85 and median = 80. A different group of 30 has a mean = 75 and median = 72. Now, what is the mean of and median for the entire group of 50?
0
votes
1answer
31 views

Quadratic fit check

I've performed LS fit to data in order to fit the following quadratic function: $$f(x,y) = A~x^2 + B~y^2 + C~x~y + D~x+E~y +F$$ Now, I would like to check that the fitted function looks like a ...
0
votes
1answer
145 views

Need help with Lagrange Multipliers in Support Vector Machine

In linear support vector machine with binary classification if we know all the support vectors, geometrically we can create hyperplanes on both sides of the main hyperplane using these support vectors ...
0
votes
0answers
153 views

Normalizing data between 0 and 1

I've got some data that I need to be normalized. I've tried several different ways I've found online, none of them work the way I'd like. I've tried ...
2
votes
1answer
199 views

Techniques to find regression parameters for multiple datasets where a subset of parameters should be the same for all datasets

I have five sets of observations of measured y as some function of measured $x_1, x_2, x_3,\ldots$ and I want to fit five functions to these observations. They have the form $$ y = f(x_1, x_2, ...
4
votes
2answers
13k views

Value range of normalization methods? min-max, z-score, decimal scaling

I am working my way through Normalization (data transformation) of data and was curious about four methods: min-max normalization, 2. z-score, 3. z-score mean absolute deviation, and 4. decimal ...
1
vote
0answers
129 views

Least squares fit or decomposition of average points (from data)

I have a set of data consisting of the averages of a function $g(r)$ at regular intervals; i.e. my first datapoint is the average of the function from $0$ to $\Delta r$, the second point is the ...
2
votes
1answer
269 views

Kalman filter for acceleremoter and gyro

I have read a lot of literature on this topic, but many questions still remain. (Many formulae are here below, so, who prefers to look at them in a more comfortable manner can find a MathCAD sheet ...
3
votes
1answer
255 views

Lloyd's algorithm in normed vector spaces

How do I run Lloyd's algorithm in a normed vector space? The space: L*a*b* color space, finite sRGB segment, $R^3$ The distance metric: CIE94 using L*C*h* information derived from the L*a*b* ...
1
vote
3answers
8k views

Find the median given a table of relative frequencies

I came across the following GRE question. I had no problem finding the mean. However, the answer for the median is given to be 1. I don't understand how they arrive at this. Find the mean and ...
0
votes
1answer
31 views

Rate of Growth of pyramid structure.

This might be simpler than I'm making it out to be, but how can the growth rate of the pyramid structure be represented. ...
0
votes
2answers
75 views

Numerical integration of a derivative dataset

I have an experimentally measured derivative data ($\frac {dy}{dx}$) at a range of times i.e $\frac {dy}{dx}$ for $0 \le t \le tf$. Integrating for $t=0$ is fine, since $y(x,0)$ is known. However, ...
1
vote
0answers
51 views

How to understand the task about bootstrap?

I have the following task. Let $X_1,\ldots,X_n$ be a sample (i.i.d.), $T_n = \overline{X}_n^2=\left(\sum\limits_{i=1}^nX_i\right)^2,$ and $\hat\alpha_k ...
0
votes
1answer
298 views

How to determine a function from outputs

Given the following inputs and outputs to a function, how would I determine an algorithm to fit? ...
1
vote
1answer
380 views

Normalize data with large spread in values.

I'm currently trying to rank a set of data. The issue is that my initial rank comes from a search on google and the returning result set. The spread in values is ranging from 33 all the way up ...
1
vote
0answers
43 views

problem in dimensionality reduction

I am using multidimensional scaling to plot my data in R. However there is a hierarchy in my dataset which i want to exploit and I am using the delaunay triangulation to visualize the plot. So now I ...
1
vote
1answer
179 views

Mathematical calculation to regenerate numeric series

I am searching for a mathematical technique by which I can perform the following, Let me explain first what i want to do. consider a numeric series: ...
2
votes
2answers
9k views

Use a set of data points from a graph to find a derivative

I have a data logger that is recording the temperature readings from thermocouples at a specific interval. This gives me data points that I can graph where the x-coordinate is time and the ...
0
votes
1answer
168 views

Dividing data of a given distribution

Having a dataset with distribution $p$ (e.g. uniform or normal), if we divide the dataset into $n$ parts with equal size, is it valid to say that each part still has distribution $p$?
0
votes
1answer
113 views

noisy 1-second GPS data [closed]

So, I come from a programming background, but not a mathematical one. I have a problem that I'm sure has a great mathematical solution! so, I have GPS data points for every second of a drive a car ...
1
vote
1answer
53 views

Box Plot Log Scaled?

When making box plots to represent data, is it logical to set our axis scale to logarithmic? Or does that defeat the whole point of a box plot?
2
votes
1answer
387 views

Group mean vector and common group covariance matrix in discriminant analysis?

I'm looking over the answers for old statistics exams in preparation for my own exam, while reviewing a question concerning discriminant analysis I found something really odd. I have input variables ...
0
votes
0answers
44 views

What is the name of the matrices which reorder edges in an adjancency so that they are closer to the diagonal? (modularity/structure)

I have seen adjacency matrices presented where the edges formed box like formations along the diagonal (not block matrices). This helped view the modularity and community structure of the group of ...
1
vote
1answer
96 views

Comparing two ratios with tolerances

I'm trying to figure out what the most robust way to compare two ratios is. What I have is a set of proportions between two or more quantities. For example, it might be 0.5:0.5, or 0.45:0.2:0.35. Then ...
1
vote
0answers
304 views

Classification: Why k-Nearest Neighbor method is more appropriate for a Mixture of Gaussians?

I'm reading a book named "The Elements of Statistical Learning" in which it states 2 scenarios when we are trying to predict the class label: Scenario 1: The training data in each class were ...
2
votes
1answer
131 views

Find data to perform regression analysis

I'm trying to find some data (two continuous variables that I believe are correlated) online for which I can perform a regression anaylsis, my assignment sheet says: The data may be found anywhere ...
1
vote
0answers
29 views

Extrapolating parameters for a fit different from the one originally used for regression analysis (no longer having access to data)

Say I have some data, I assume a fit of the form: $\alpha_1 e^{\beta_1 k}$, and I extract some values $\alpha_1>0$ and $\beta_1<0$ for $k=[1,\ldots]$. Say this appears to be a "near perfect" ...
1
vote
0answers
145 views

How can I create a good subset of data proportional to the full data set

I am programming a neural network and I need to use some data to train it. I am following the steps of an experiment which tried to predict direction of stock price index movement using neural ...
1
vote
0answers
38 views

How to find BUE of N? where $X_i$ iid $ P(X_i=j)=1/N$, for $j=1, \cdots, N$

Let $X_1, \cdots, X_n$ be iid with $P(X_i=j)=1/N$, for $j=1, \cdots, N$, where $N$ is an unknown positive integer. I would guess that the order statistics $X_{(n)}$ is the complete sufficient ...
0
votes
0answers
18 views

Linear trend has to pass through a point [duplicate]

Possible Duplicate: Linear trend has to pass through a point I need to interpolate a linear trend surface through a number of points but with the condition that the surface has to pass ...
0
votes
0answers
174 views

Test of goodness of fit - normal distribution of file sizes on HDD

I'm trying to prove, that sizes of files stored on HDD comes from normal distribution. I already made a java code that gave me list of all files on disk with filesizes in Bytes: ...
2
votes
1answer
577 views

Data Type Classification in Statistics

It is my understanding that in statistics one has 4 basic data types: nominal, ordinal, ratio, and interval. I see cases where people refer to "count data" (which is a random variable whose range is ...
0
votes
4answers
333 views

Can you help me solve these questions related to a Logical theory?

In a group of 200 people, number of people having at least primary education (assuming - Category I): number of people having at least middle school education (Category II): number of people having ...
0
votes
1answer
82 views

Determining Sample Size - Design Problem

I have a hypothetical problem were say I have a sample size of about 5000 people. I then will collect data on them say, how man calories of food they eat per day for a month. Now I can't obviously run ...
1
vote
1answer
130 views
0
votes
1answer
108 views

algebraic expression for a counting function

consider a 2d "counting" function given by the $(x,y)$ points/pairs: (1,1), (2,2),(3,2), (4,3),(5,3),(6,3), (7,4),(8,4),(9,4),(10,4), (11,5),(12,5),(13,5),(14,5),(15,5), ... ie $x$ increments in ...
9
votes
3answers
542 views

Removing noise when the signal is not smooth

Suppose we have (an interval of) a time series of measurements: We assume it can be explained as a "simple" underlying signal overlaid by noise. I'm interested in finding a good algorithm to ...
0
votes
1answer
73 views

What is the name of this data normalization?

I have a two-dimensional array ($569\times30$ double) which should be normalized using this formula: $x'_{ij} = \dfrac{x_{ij} - \overline\mu_j}{\overline\delta_j} $ What is the name of this ...
0
votes
1answer
71 views

Finding outliers in a linear series

I have a series of observations made against time. Given perfect observations, the trend should be reasonably linear. As I expect there to be measurement errors, I wish to exclude them from further ...
1
vote
1answer
584 views

Error in a numerical derivative

I have a graph of data, say temperature ($T$) vs time($t$), I know the error bounds in each $\Delta T$. The range of t is from 0 $\to$ 1600 s, with small steps say 0.001 s. If I numerically take ...
0
votes
1answer
70 views

Determine a curve's dominant direction over time

I have a sequence of numbers in a certain order, for example {60,61,62,1,63,,64,102,65,66,200} If this is drawn as a graph, this will be a curve going upwards, but with some aggressive jumps upwards ...
1
vote
2answers
2k views

What is the distribution of a data set

I understand what the probability distribution is. I also have a personal understanding/interpretation of the concept of distribution of a dataset. Whenever I see this expression I imagine a graph ...
5
votes
1answer
730 views

Abstract Algebra for Business Intelligence / Data Mining

Twitter released its Algebird library, an abstract algebra library for scala. At a high level, what are the maths involved in abstract algebra that have an impact on aggregating large datasets?
3
votes
2answers
133 views

How do I use specific data points on a graph to determine an equation?

I need to find a function $f(x)$ such that the following data points would fit on it: $$f(1) = 0 \\ f(2) = 0.5 \\ f(4) = 1.0 \\ f(8) = 1.5 \\ \cdots $$ and so on. So the pattern is every time $x$ ...
0
votes
1answer
146 views

Microsoft Excel not graphing, $x = y^{1/2}$

Im not sure if this is a math question or a su question. The experiment was relating the period of one "bounce" when you hang a weight on a spring and let it bounce. I have this data here, one ...
1
vote
0answers
49 views

Fitting multiple functions with shared parameters to data

consider a set of real-valued continuous functions $$f_i(t;a)$$ for $1\leq i\leq n$ with some shared non-negative parameters $a=(a_1,\ldots,a_d)\in\mathbb{R}^d$. Furthermore, assume that there exists ...
1
vote
2answers
134 views

Finding an equation to fit data points

I'm a software developer by trade and one of the things I did today was recursively generate some dummy data for a tree. I used two parameters in my recursive algorithm: number of levels and number of ...
1
vote
0answers
99 views

Filter/Removal of periodic 'delta-peaks'

Currently I am measuring data (Counts over Time). Due to measurement problems I have some nasty peaks in this data. These peaks are periodical, very sharp (~3 datapoints over a range of 10000) and ...
2
votes
1answer
95 views

What's the best function to use to fit this data?

{7502, 6610, 4988, 2861, 2242, 1746, 1433, 1312, 949, 793, 767, 664, 660, 653, 588, 578, 575, 572, 553, 500, 445, 418, 374, 165, 108} I was looking at the number of seeds for torrent files for ...
0
votes
1answer
47 views

arctic sea ice data by year

I want to demonstrate the usefulness of regression lines to my class, and I was hoping to do so with some data about the Arctic sea ice. What I'd like is the maximal area covered by the ice per year, ...