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.
-3
votes
0answers
48 views
How to calculate the equation of a curve?
How to calculate the equation of a curve ? Following are the Data for the curve.
...
1
vote
2answers
26 views
Curve fitting: $a f_1(x)+b f_2(x)+c f_3(x)+d f_4(x)$
I want to fit my data $y$ with a method such as
$$a f_1(x)+b f_2(x)+c f_3(x)+d f_4(x)$$
However I don't know how to obtain coefficients $(a,b,c,d)$ of the known functions ...
1
vote
2answers
37 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
25 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 ...
-1
votes
0answers
35 views
Statistical Analysis- Pre and Post-survey Data Analysis [closed]
I am doing a research project on whether or not students are aware of the benefits of graduating from high school. I gave students a pre-survey, then gave a presentation, then gave the same students ...
0
votes
1answer
18 views
How do I handicap a leaderboard?
In a game scenario, where each player can score points based on the number of "opportunities" they are given, but where some players have many more "opportunities" than others, what is a good way to ...
0
votes
1answer
22 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
27 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 ...
0
votes
1answer
33 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, ...
0
votes
1answer
208 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
votes
1answer
17 views
Relationship between two variables that does not seem correlated [closed]
I want to know the relationship between age and cholesterol level in a certain population. I have gathered a 200-person sample. After visualizing the $(age, cholesterol)$ pairs as a scatter point ...
0
votes
0answers
52 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 ...
0
votes
0answers
23 views
Variogram practical interprtation
I have 23 stations and I have calculated the variogram as following:
Variogram
The maximum distance between the stations is 2169 meter and the range is 1650 meter (exponential effective range).
I ...
2
votes
0answers
63 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 ...
1
vote
1answer
78 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* ...
0
votes
0answers
13 views
Finding the number of measurements given a boxplot.
I am trying to do the following GRE question, and have difficulty with part (b). The answer is 40 measurements. I have no idea of the procedure to do this part of the problem.
1
vote
1answer
48 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.
-1
votes
1answer
18 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
60 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, ...
0
votes
0answers
25 views
What's the problem will I have if the variables in an object function are not independent?
I have a question related to objective function minimization. Suppose the object function can be written as sum( (erf((xi-p)/delta) -yi)*(erf((xi-p)/delta) -yi) ), ...
1
vote
0answers
37 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
0answers
57 views
Choose a right optimization method
I have a question related to optimization method selection. Suppose now I have some observation data (1D) as well as the underlying function model. For example, I use the following codes to generate ...
0
votes
1answer
32 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 ...
2
votes
0answers
33 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
98 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:
...
1
vote
2answers
80 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
33 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
76 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 ...
0
votes
0answers
32 views
Splitting a dataset with a given distribution?
Having a dataset with a given distribution $p$ (e.g. uniform or normal), if the dataset is randomly split into $n$ sub-datasets with equal size, is it valid to say that each sub-dataset still has ...
0
votes
0answers
13 views
For unequal size clusters, how do you estimate probability for initial centroid
I've read that for equal sized clusters, the probability that centroid could come from any cluster is K-factorial/K exp K.
But what if clusters are unequal? And doesn't intercluster distance matter?
...
1
vote
1answer
24 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?
0
votes
1answer
30 views
How are user opinions compared?
Consider a situation where people are asked to rate a product on a scale of 1 to 5.
Product A has a rating of 3.95 based on 15,000 ratings. Product B has a rating of 4.2 based on 1000 ratings.
...
1
vote
1answer
71 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
37 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
43 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
40 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
30 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 ...
0
votes
0answers
69 views
Problems with Percentage Change for Trending data [closed]
Firstly, I have a very minimal understanding of any high level mathematics but I'm hoping this has an fairly basic answer. I searched other questions before posting this and didn't find anything ...
1
vote
0answers
23 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
45 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
28 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
71 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:
...
0
votes
0answers
56 views
maximum likelihood discriminant rule
I'm trying to use maximum discriminant rule to classify objects in my database. Could, please, somebody clarify the following for me:
For example we have 3 groups and we already know what groups our ...
2
votes
1answer
117 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
286 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
45 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
74 views
0
votes
1answer
38 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 ...
7
votes
3answers
125 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 ...
