ancova

  1. B

    Shapiro-Wilks significant, all other indicators NORMAL

    Hello everyone, I am checking my assumptions before running an ANCOVA, one of which is that the DV is normally distributed across all levels of the IV. MY IV is 3 groups (Ns of 32, 31, and 32) and my DV is a continuous variable from 1 - 5. Before splitting into groups, it looks normal and the...
  2. D

    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...
  3. T

    ANCOVA or oneway-ANOVA on gain scores

    Hi everybody. I'm curious to know which is the most correct/preferred method to analyse my data. I've got a randomised clinical trial with three groups(placebo(n=24), low dose(n=21) high dose(n=21)). There is pre and post measures on a 40+ continuos variables. I've performed ANOVA at...
  4. D

    Do i use an ANCOVA for a cross over of exams, pre/post study?

    I have a study i am running and would like to know the appropriate test to apply, its complicated but bear with me :) Background: We are looking at assessing the effect a series of optional tutorials delivered during a semester has on test scores in a cohort of students. There will be a...
  5. M

    ANCOVA coding of categorical covariates

    Hello all, I am running an ANCOVA in R (Anova function) to assess the results of a randomized experimental study. I have a 2x2 full factorial model that will control for three continuous and two categorical covariates (ethnicity and gender). The gender covariate is unbalanced with a breakdown...
  6. P

    ANOVA vs MANCOVA

    Hello. I'm doing a study on people with high vs. low self-compassion and I want to compare them on a number of variables. Self-compassion in this group varies by age, so I want to do ANCOVAs to compare means while controlling for age. My question is this: since SPSS only allows you to do...
  7. M

    ANCOVA versus regression: Independence of the covariate and treatment effect.

    Hi, if you read about the assumptions of an ANCOVA, you find the following assumption: "independence of the covariate and treatment effect". That is, the treatment effect should be randomly distributed between groups representing the treatment, and can be checkt via a T-Test. I dont...
  8. A

    Repeated measures ANCOVA in SPSS help needed with multiple covariates

    Hello everyone. Hope someone can help. I have a repeated measures (4) ancova I need to run with no between subjects factor. I have 5 covariates. Im trying to get the effect of 1 covariate on the repeated measures when accounting for the other 4 covariates. How best to do this? Thanks in...
  9. C

    ANCOVA - can I delete a very significant variable from a model's equation?

    Hi all, I undertook a sensitivity analysis to study the contribution of explanatory variables to soil organic carbon variations. Here, the explanatory variables were the soil, climate, fertilization, tillage, stubble and rotation managements. Since we have a linear model, a combination of R2...
  10. P

    Comparing two factors in five areas

    I recently compared two factors in five different areas testing diversity of one factor against another. (Diversity was made quantitative for comparison using the Simpsons Diversity index) I received a very strong positive correlation between one diversity against another and between areas with...
  11. T

    ANCOVA with more than 2 covariates. homogeneity of regression slopes.

    Hello, I am carrying out a ANCOVA with more than 2 covariates with SPSS. I want to check the homogeneity of regression slopes to confirm the assumption. When in a ANCOVA with one covariates, I can understand. https://www.youtube.com/watch?v=oNX8hL6QHNM When in a ANCOVA with more than 2...
  12. M

    Multiple Regression: 3 levels in IV of interest, how to compare between all 3?

    Hi all, I would like to test the following and am hoping to get some assistance as I am new to regression: DV - Brain volume IV - Participant Group (Patient with Mild Symptoms, Patient with Severe Symptoms, Controls) Covariates - Age, Gender, IQ I wish to use multiple regression in...
  13. P

    Unequal sample sizes, unequal variances, help my ANCOVA!

    Hi everyone, I am trying to test to see if there is a difference between the means in two populations. Population A: 100 people, controls Population B: 330 people, anorexic I want to see whether they differ on a measure of body checking (ex: pinching fat). I'm using SPSS...
  14. F

    Linear Regression with effect size changes of categorical variables with continuous

    I have three categorical variables (disked, herbicide, Lands) each is binomial (0,1). For example, within disked there is a group in which it does not occur (0) and where it did occur (1). I am performing a forward stepwise-approach in which I evaluate each categorical variables in the order...
  15. S

    repeated measure ancova

    Hi, I do have a rather simple question but could not find a direct answer on other forums. I ran a repeated measures ancova with time (2) as within-subjects factor on accuracy rates (so that one was measurd twice) and entered age as the covariate. in the between-subjects table the...
  16. R

    Replication: Strange flip of signs in regression

    Dear all, I have successfully run an experiment 2 times. I predicted an interaction between a dummy variable (intervention 1-yes/0-no) and a metric baseline (T1) affect measure to predict the same affect measure at T2 (post intervention). The intervention succesfully buffered the effect...
  17. J

    Working around a significant Levene's test in an ANCOVA?

    Hi there, I'm working with some data in which I'm looking for mean differences across 15 subject categories of data on a variable (Clicks) that also covaries with another (Time). I'm trying to control for Time to neutralize its effect on the mean differences in which I'm interested. I've...
  18. J

    HELP - One-way ANOVAs/planned comparisons/correlation

    Hi all, I'm currently running a Psychology experiment: the effect of background music on memory and mood. I will be using SPSS to conduct two one-way ANOVAs (music + mood / music + memory), w/ planned comparisons. However, I also want to see the effect of mood on memory but I don't know how...
  19. J

    One-way ANOVA and planned comparisons - HELP!

    Hi all, I'm currently running a Psychology experiment: the effect of background music on memory and mood. I will be using SPSS to conduct two one-way ANOVAs (music + mood / music + memory), w/ planned comparisons. However, I also want to see the effect of mood on memory but I don't know how...
  20. B

    Workshop evaluation with control group and pre/post/follow-up questionnaire

    Hello, Thanks for taking the time to read this rather long message. It will become clear that I have a terrible grasp of data analysis and need some help. I have read and read and read and am still very confused. Any help is greatly appreciated. I have to design the evaluation for a health...