regression

  1. C

    NLS with real data

    I have data that has length, age and density (counts) and i am trying to model this data to see if density at birth has an influence on length. Since my response variable reaches a plateau i know i will need a non linear model. Can anyone help me with how to go about fitting a non linear model...
  2. P

    Selection bias in categorical independent variable in regression analysis

    I have an issue with selection bias in my independent variable and I am uncertain of the best approach to correct for it. I'm looking at soccer data and trying to make some forecasts on players from different amateur level clubs to what they might be expected to do at the professional level...
  3. C

    A simple explanation of regression for multiple baseline design?

    Hey guys. I’m doing a single-case, multiple baseline design study. It’s likely that visual analysis will show significance, which means I’ll need to do a regression-based analysis, as recommended by the What Works Clearinghouse. In my proposal I need to write 2-3 simple sentences about what...
  4. M

    Which test should I use for a within-design with only one measuring point/time?

    Hi, I will lay out the experiment I am analyzing shorty and a little bit simplified: Participants were asked to debate a topic with an experimenter. The participant's debating strategies were observed and scored. For example, every participant obtained a score for "negative strategies" (NS)...
  5. R

    Using average response time as an outcome variable

    Hi all - I am working on regression analyses with timing data as the outcome variable. Specifically, I trying to estimate questionnaire item response time based on item attributes (e.g., item content, number of response options, etc.). I am sure there are respondent factors that impact response...
  6. F

    Solving an autoregressive equation

    Hi, has anyone an idea how to solve this equation: y_t - y_t-1 = c + delta*t + phi*y_t-1 + eps_t I would be super grateful if anyone could help. Cheers!
  7. N

    Significant treatment*pretest interaction, but interaction not shown with regression lines

    Hello, I have found that the interaction treatment by pretest is significant. However, the interaction is not depicted on the scatterplot (see attachments). Am I doing something wrong or can I say that the interaction is outside the range of possible test scores (0-10) and that the assumption...
  8. N

    Can this problem be modeled?

    I have a question about whether I can model in a way that solves this problem: Suppose a swimming coach has 100 athletes and only cares about the distance they can each swim in 5 minutes. From this, he sets a baseline expectation of each swimmer’s "5-minute distance" expectation that is...
  9. M

    Recreating logistic regression model in SPSS

    Hello everyone :) I would like to ask for advice regarding recreating a logistic regression model (please see the picture attached). I am working with household level data (English Housing Survey) and on the top of the already present household-level variables, I would like to construct...
  10. S

    Help with interpreting log in regression

    Good morning, I am new to this forum and would like some help with the interpretation of the following regression. I hope I am in the right place. lnWaste = +A(lnGDP) +B(lnGDP)2 I have found coefficients for lnGDP= -1.85 and for (lnGDP)2=0.1 Now I am trying to give an interpretation of what...
  11. Reductionist

    pre-publication testing of one-click auto-analysis tool

    Hi all, I’m a psychometrician at Penn (https://scholar.google.com/citations?user=TlO7ZTsAAAAJ&hl=en) and wanted to get your feedback (as students, faculty, or private sector folks) on a new tool I’m developing for one-click automatic data analysis: https://mooremetrics.com/deedive All you have...
  12. T

    Logistic regression in Stata with binomial dependent variable 3-level categorical predictor variable

    Hi, I'm doing a logistic regression analysis with a binomial outcome variable (Yes / No). My main predictor variable is categorical and has 3 levels. I'm also including categorical and continuous confounding variables as predictors. What is the best way to convert my outcome variable from...
  13. A

    How to interpret the intercept in a regression model which has a categorical covariate?

    I have a regression model with some response Y and covariates height, weight, age, sex. Sex is the only categorical covariate and it takes on the value Sex = 0, for female Sex = 1, for male I want to interpret the intercept of this model, that is the estimated mean value of Y when all the...
  14. A

    How to choose between two regression models when one has a higher adjusted R^2 and the other has a lower BIC?

    I have two regression models with different number of covariates/predictors. After performing a subset selection, the remaining two choices are Model 1, which has 7 covariates and a lower BIC. Model 2, which has 11 covariates and a higher adjusted R^2. Using the BIC criteria, you select the...
  15. M

    Replacing regressor instead of 2SLS

    Hi, can someone explain me why it is usual to run a 2SLS if we are not "satisfied" with one variable and using an instrumental variable to adjust the model? (I am just talking about the just-identified case) Wouldn't it be easier just to replace the variable with the new one, so we have a new...
  16. R

    Interpretation of interaction terms in a multiple linear regression

    I try to improve my statistical knowledge and right now I am working on a regression that contains interaction terms. I am currently investigating the effects of different variables (a1, a2 etc.) on the quantity of chairs sold in a transaction (dependent variable). To see if effects are...
  17. R

    Help to formally write down a linear regression

    Hello altogether, i am currently analysing a dataset of 10,000 transactions. I am analysing the effect of different advertising campaings on the quantity of chairs by using multiple linear regression model with zip code and day dummies. I am interested in formally writing the regression model...
  18. J

    IVs and moderator variables correlate in three-way interaction - problematic?

    Hi everybody, let's assume I hypothesize: H1: A direct effect of X1 on Y H2: A direct effect of X2 on Y H3: A two-way interaction between X1 and X2 H4: A three-way interaction between X1, X2 and X3 H5: A three-way interaction between X1, X2 and X4 and run the following OLS regressions to test...
  19. S

    Constant not sig. in multiple regression - does it matter?

    I did a hierarchical multiple linear regression in SPSS with three predictor variables. All the variables have high F-values and are highly significant at each step of the model, but the constant is not significant (0.079) in the last step. Should I disregard all the results just because of...
  20. S

    Regression Question for Measuring a Corporate Campaign

    Hi everyone, I hope you are all having a great day. Currently, I am trying to measure the effect of an in-store campaign that deals with sampling items. I have 80 stores (40 control and 40 test). I have many interesting variables, such as average local income, number of competitors within X...