# regression

1. ### a completely randomized experimental design and regression

A company studied the effects of three different methods of promotions on sales of its crackers (labeled as Treatment 1 to 3). Fifteen stores were selected for the study and a completely randomized experimental design was utilized. Each store was randomly assigned one of the promotion types...
2. ### predicting a rv based on past time series results

Hi all, I have 3 previous years data (ie 3 time series) going from 05/05 may 05 - august 25 , the curve for the current year has data plotted from may 05 to may 26th (plotted every Thursday) so how would I use the previous data to predict the curve into the future? Time Series does not...
3. ### [R] How to get normal/ rankit scores from non-normal data with ties.

Hello, I would like to see whether pathogen levels influenced certain bumblebee colony development parameters such as the number of queen pupae produced. Due to non-normality of the data I would like to do a rankit transformation of the data as suggested by [Bishara & Hittner (2012)][1]...
4. ### dummy regression - unequal sample sizes

Hello, I am conducting a linear regression analysis in SPSS with different variables: - scale, - 2-level nominal, - 5-level nominal (dummy) The sample sizes / frequencies for three of the five levels of my last dummy variables are under the recommended 15% (namely 12,5%, 5% and 5%). Can I...
5. ### Help for simple regression

My research question is: "Can we say that the number of hours of Internet use increases with Internet purchase?" with the variables: - Use of Internet per week (Use in hours) - If respondent has already made a purchase on the Internet (1 = yes, 2 = no) This statement clearly tell me...
6. ### Imputing Missing Values using Regression

I have a table of 4 variables where some of the data is missing and I need to impute the missing values, my table is as follows: X1 X2 X3 X4 1.0 20 3.5 4 1.1 18 4.0 2 1.9 22 2.2 - 0.9 15 - - My notes for this material a quite...
7. ### Stepwise Regression Limitations Explanation

I've recently been working on building a model and have come across a number of different approaches. I'm particularly interested in the limitations of using Stepwise regression as it has a huge amount of criticism online, however I can't find much material detailing why it's a poor method to...
8. ### Linear Regression Interpretation

Hi there, I am running a Multiple Linear Regression analysis. I have 2 predictor variables (self-worth and self-acceptance) and 1 criterion variable (self-esteem). As hypothesized, self-worth and self-acceptance reliably predicted the scores on self-esteem (eg. higher scores on the...
9. ### Help for mediation

Hi, my research question is: "Can we say that the number of hours of Internet use increases with Internet purchase? This influence of Internet purchase on the number of use can it be explained by an attitude becoming more favorable to as we know Internet? " my variables are: - Use of Internet...
10. ### Package similar to relaimpo for binary regression

Dear all, I have a quick question that I’m really hoping you can help me with. I’m looking for a similar package to relaimpo that can be applied to binary/logistic regression in R. More exactly I am trying to find a way to compute the importance of each predictor in the case of a binary...
11. ### Multiple, hierarchal regression - division of p-value?

Hey everybody! I am pretty new to this forum and also to statistics. In these days I try to analyze the data for my Bachelor thesis. I study psychology in the north of Germany. Well, my questions refer to the process and the output of my multiple, hierarchal regression. I have two...
12. ### Regression to compare mean differences?

Hi everyone, I am doing a project with two different groups (clinical and control). I want to compare their scores on a couple of variables (ex: body image disturbance), while controlling for age and BMI. My committee member recommended I do a regression, and noted that it would allow me...
13. ### Anova or Chi Square for checking significant related effects

Hi, I am a newbie to Data Analysis and would be thankful if you could explain to me if for this exercise I use Chi Square or Regression ( looking at the ANOVA table). For each what would be the specific steps? For example for Regression which is the dependent variable, etc. Exercise...
14. ### Compare two regression models

Hi all. I have a standard (level-level) regression model and a regression model which has the same independent variables except one of the independent variables are in log form. How could go about comparing the two statistically speaking?
15. ### Box-Tidwell problems in SPSS (Logit Regression)

Hello everyone I am currently performing a logit regression in SPSS. I am faced with problems when testing the linearity assumption using the Box-Tidwell approach. I have 10 continuous variables and for each of them I have computed their Natural Logarithm. For testing the assumption, I...
16. ### Comparison of regression coefficients between (nested) geographic regions

Hi All, I would like to compare the effect of an explanatory variable (say X1) on a response variable (Say Y) between two geographic regions in which one is a sub-region of the other. For example, I am fitting two regression models(Y on X1), one for the city data and the other for country...
17. ### Question on the merits of mediation analysis Vs another analysis (described within)

Hello, I have a dataset involving an intervention (placebo versus real) - denoted as X, an outcome (Y), and a physiological variable (M) that I hypothesised would mediate the effect of X on Y. I have shown that X did not significantly affect Y (as assessed using simple linear regression), but...
18. ### Regression - Make a new group from data

Hi. I am new to R, and have to do a regression on the dependent variable but only for a certain group which is characterized by one independent variable1 = 1 and another independent variable2 = 2. So, the regression in question should only be done for the observations which comply with the...
19. ### Predicted Probability

Someone created a spreadsheet to graph predicted provability values on a Logistic Regression S Graph. There are four values used. a = Assumed Maximum b = Assumed Minimum c = Raw Data St. Dev (Field Data) d = Model Output (Research Data) the formula used if the following NORMSDIST...
20. ### Gravity model

Hi I am currently writing an assignment regarding a trade model using a gravity equation. The dependent variable in the model is Ln(X) and the non-dependent is both Ln (GDP, distance and so on) AND binary variables. So the question is: can I use SPSS for this kind of modelling or would...