1. R

    Conceptual queries in modeling

    Hi all, I am from engineering background. I would require your help in certain conceptual questions in modeling. Your help would be greatly appreciated! Following are my few questions... (Pointers on these questions would help me , else you may direct me to any useful resources.) 1)If a...
  2. M

    Violating Homogeneity

    Hi, if in regression models homogeneity is violated, the variance can in principle depend on both: Predictor and outcome variable(s). In case of a dependency on categorical or continuous predictor variables, there are many ways to model different dependencies, e.g. using GLS models. In...
  3. I

    Problem log(0) practical solution?

    Hello everyone, I want to model the association of a score (range 0-125) and age with an exponential approach because my scatterplot show an exponential progression. My approach is: I do log(score) -> do a linear regression with age as covariate -> do exp(regression coefficients)...
  4. K

    [SAS] Compare predicted vs actual continuous [0,1] data

    Hello, I have predicted values for year and quarter that were calculated from a linear regression, and I also have actual values. I would like to compare the actual vs. predicted values to ensure that the model was appropriate. The data are continuous on [0,1]. I had tried a chi-squared...
  5. S

    Questions in implementing Considering Canonical Correlation Analysis in R

    I have a dataset of temperature readings of different burner parts which determine the final temperature of the burner and time to set off burner So my dataset looks like this: Knob_reading_of_Coil_temperature(P1) Knob_reading_of_barrel_temperature(P2)...
  6. S


    If you wanted your null hypothesis to be that y and x are linearly related, and your alternative to be that they are quadratic. What could you use as your null and alternative hypothesis, and how would you go about testing it?
  7. O

    Estimate a Logistic Regression Model

    Hi guys, I want to estimate a logistic regression model's equation based on observed data and get the coefficients to extrapolate further. I have two inputs (one interval and one ratio) and one output (between 0~1 probability). Interval Ratio Odds 5 0 0.00% 10 1 0.00% 15 2 0.00% 20 3...
  8. B

    bayesian statistics

    I have a large amount of data, given totals for every hour over a year period for the following columns: # of Jams Jam event time in minutes # of Full occurances Full event time in minutes and Runtime, product flow (counts) I am trying to create a bayesian model using iPython and...
  9. C

    Ranking a Location using Linear Regression

    Hi, I am facing a strange problem with a software patented in the USA. It is a location evaluation software, which offers insights on determining the best location for starting-up a gas station / petrol station. While reading the patent thoroughly, I feel that the software operates based...
  10. S

    regression on age groups

    Dear All, I have the following question: Estimate a simple regression model of ‘libertarian-authoritarian’ attitude as a function of age groups and comment on the sign, significance and magnitude of the effects. I have one variable (and only one) called AgeGr and the age groups are 18-25...
  11. B

    Why one-tailed sig. in SPSS Regression Correlation

    Given that a two-tailed significance test is usually preferred unless one has a hypothesis about the direction of the relationship, why in the Regression descriptives output does SPSS default to a one-tailed test for the correlations, without any way I can find to change it to two-tailed?
  12. M

    Regression with Differential equations (ODEs / PDEs)

    Hi, in the field of mathematical modelling of biological or physical processes, most of them cannot be described by simple (linear or nonlinear) relationships between predictor X and outcome Y, but only implicitly via differential equations, such as Ordinary differential equations (ODEs) or...
  13. P

    A coefficient to determine Variance

    Hi I am working on a system where temperature stabilises with distance but also increases/ decreases based on month/ hour. Is there a way to tell the model that the variance will decrease with distance? Thanks PYork
  14. S

    Increasing variables decreases DFs?

    I'm sorry if this is a total noob question, but I cannot figure it out. When I'm adding variables into my regression into STATA, the degrees of freedom (and observations) decreases significantly. In particular, adding one variable decreases them by about 1,000. I am only looking at the same 6...
  15. H

    Linear Regression: Disagreement in confounding with stratification

    Hi everyone, I am performing a simple linear regression testing whether an the results from an aptitude test for our sales force is associated with their profitability (binary variable profitable or not). The score variable is a percentile. I performed a simple logistic regression...
  16. J

    Help with Hat Matrix

    considering the model Yi=β0+β1Xi+ϵi, i=1,2,3,…,n how can i calculate the hat matrix and what would element hij be ? thanks
  17. D

    Sample size - have searched high and low,bu tprobarbly very quick and easy to answer!

    Hello Friends, I haven’t looked at a statistics book for a good 5 years, since leaving uni and moving into the job world. However, I have come across a real world problem where I feel there is a statistical method to help me, but after searching high and low cannot find it. I’ve looked at...
  18. L

    NFL Week 6 regression predictions Atlanta 54% NY Jets 79% Pittsburgh 52% Minnesota 73% Buffalo 55% Detroit 84% Denver 75% Houston 55% Miami 52% Seattle 59% Green Bay 80% Baltimore 51% New England 59% Philadelphia 76%
  19. L

    scatter plot for partial regression (in spss)

    Hi all I have an SPSS regression model in which I have a dependent variable, an independent variable and 4 covariates. I want to create a scatter plot for the dependent and independent variables WHILE CONTROLLING for my covariates (the way I understand the default SPSS scatter plot that...
  20. M

    Ordinal regression shows negative effect when spearman correlation shows positive

    I running a regression model where a variable is indicated to have a negative impact on the predicted variable: Estimate Std. Error Wald df Sig. 95% Confidence Interval Lower Bound Upper Bound Threshold [email_contact = 1] -4.682 .664 49.713 1 .000 -5.983 -3.380 [email_contact =...