multivariate

  1. M

    Symbolic Regression applied to multiple time series - risk of spurious regression?

    Hello together, I want to build a predictive model for sales data, and herefore I want to analyze sales data and its correlations with other time series using Symbolic Regression (Eureqa: nutonian.com). In traditional multivariate time series analysis (e.g. VAR models) there is the risk...
  2. M

    Extend economics thesis with multivariate analysis

    Dear all, Working on my Master Thesis I got the remark from my supervisor that I have to extend the research with a multivariate analysis. I have been looking at literature, text books and different forums how to approach this, but could not find any usefull sugestions. If anyone could help...
  3. R

    Multivariate repeated measures, binary and continuous

    Hello all. I am working with a data set of multivariate repeated measurements. Specifically, subjects performed an exercise they were taught up to three times each and recorded heart rate variability (HRV) and whether they felt a particular sensation (details omitted). Whether they reported...
  4. J

    Redundancy Analysis - how to interpret the plot

    I'm reading a paper that uses a redundancy analysis but I don't know how to interpret the figure. It seems like such a basic thing that I should understand, but I'm having a hard time finding anything that answers my questions. - What do the axes mean? - What does it mean when arrows point...
  5. J

    When to use Multivariable vs. Multivariate?

    Hi - I recently met with a statistician to discuss some of my data, and learned quite a bit, but was still left with some questions. I have learned that there is a difference between multivariable and multivariate data; however, I am not certain when to use each approach. I understand that...
  6. J

    Statictical suggestion regarding DOE and GLM for the pharmacutical related problem

    We performed a DOE to study the relationship between simulated intestinal fluid (SIF) components and solubility of drugs. The DOE is composed of 7 factors (representing the components of SIF) and 2 levels for each drug. And we have done several drugs with the DOE. Now with the DOE analysis, we...
  7. victorxstc

    Univariate, Bivariate, Multivariate: Myths and facts

    This is not a question but a summarization of my recent learnings regarding the common mistakes in calling different types of analyses, and to address the proper names for them. I now know that a multiple regression is not a multivariate analysis, although I have seen millions of incorrect...
  8. R

    Multivariate regression

    Hello, I am using SPSS 20.0 and am running a multivariate regression using the GLM procedure. I would like to know how to test whether the relationship between one independent variable (X1) and one dependent variable (Y1) is...
  9. R

    Regression with 4 highly collinear IVs and 4 DVs, best approach?

    I have a dataset consisting of four continuous independent variables with a value between 0 and 1, and four continuous dependent variables with a score between -3 and 3. The IVs are values representing a same biomarker, but in different regions of the brain. The DVs are values representing four...
  10. S

    Is there a test to see if a sample (one result, many parameters) is an outlier?

    I am posting here because I am not sure really how to look for my answer. I am used to comparing means of two samples, but what happens when you have only one sample but 20 parameters? How do you determine if this is significantly outside the data cloud for a data set that has about 100 samples...
  11. K

    Updating covariance matrix when more info becomes available.

    Say, I have a solution to a 3D problem in the form of a a triple (x0,y0,z0) with uncertainty specified by an error covariance matrix S. Using these one can calculate and plot say the 1 sigma ellipsoid around this solution. Now suppose someone tells me that my solution "z=z0" is in fact...
  12. M

    NEED HELP with understanding when to use what method

    I have been trying to familiarize myself with statistics but I'm getting confused on what methods to use when answering what questions. For instance, if I want to determine which of a set of tested parameters (A, B, C, ...) are significantly different between two groups, would I use a t-test...
  13. M

    Correlation multivariate trinomials

    I have a dataset of 6 multiple choice questions with each question having 3 mutually exclusive choices. The dataset is split into a number of time frames where each time frame hold, say, 1000 questionnaire results and each of the 18 datapoints provided in the time frame hold the fraction of...
  14. S

    Three-way PCA

    Hi all, Does anybody have experience with 3-way PCA? Is there any example using SAS? I am not sure if I understand how it is different from the classical PCA... Thank you
  15. O

    Conditional Multivariate Probability

    So, I got this from my textbook and it makes sense: P_{Y|x}(y)= P(Y=y|X=x) = P_{X,Y}(x, y)/P_X(x) But I'm trying to apply it to this question and I'm struggling. Here's the question: Suppose a die is rolled six times. Let X be the total number of 4’s that occur and let Y be the number of 4’s...
  16. B

    Multivariate equivalent of a matched pairs t-test?

    Hi there, I have a multivariate data set, and I have performed the main analyses on it and am happy with the results. Now, I took duplicate measurements for half of my samples, and what I want to do is determine how repeatable/accurate my measurements were - i.e. how similar the two duplicate...
  17. F

    Using Cox multivariant regression!

    Hi I am trying to do Cox multivariate regression analysis in a project where I am trying to identify predictors of a particular disease using variables such age, X- ray findings, and other identified known risk factors, and I am wondering how to perform such an analysis using excel, or even...
  18. J

    Test selection help for multivariate response and predictors

    I need help determining what method would be applicable to the following situation. There are 2 chemicals, A and B. Also, there are two organisms, say Jim and Kelly. It is impossible to separate Jim and Kelly. Although, sometimes, levels of Jims or Kellys might be slightly more than the...
  19. A

    Univariate or Multivariate?

    Hi My data is on two equal groups of patients. The two groups have roughly equal proportions of males/females. A blood sample was obtained form each patient, and 10 of the blood components were measured either as a count, % of volume or a concentration. The objective is to see whether the...
  20. J

    simple multivariate question

    I have, I think, a simple question about multivariate statistics, and I'm not sure which test (or even what kind of test does this). I have 40 items (replicates) THEY ARE NOT IN ANY PARTICULAR GROUPS. For each item I have tracked the prices each week for a year. So I have 52 measurements of...