normality

  1. O

    Normality: DV itself or residuals?

    I always thought that we should be testing the assumption of normality by looking at the distribution of the DV in our design (by each level of the IV). But I keep seeing people talking about the residuals of the DV. For example, in ANOVA (and I suppose by extension the t-test and regression)...
  2. A

    My data does not follow a normal distribution, but Mann Whitney U test gives me a p-value of 0.935?

    As the question indicates, I conducted a normality test on Minitab, and the p-value I received was 0.018, which is less than the significance level, therefore, it is not normally distributed. Therefore, I had to conduct a non-parametric Mann Whitney U test, and the p-value is 0.935, which...
  3. J

    Normality

    I did a test of normality in STATA on my dependent variable. The rest was significant thus violations of normality. After taking the log, there is still violation of normality. What is the next step to take?
  4. L

    Likert scale data -can I use paired t-test? What about normality testing?

    Hey all! I have read many contradicting manuals and advice, so I decided to ask the best experts –you guys :) I have data from 40 subjects. I asked them to analyze eight short films (four sad ones, four neutral ones). I asked them to rate on a Likert scale 1 (not at all)-5 (very much) how much...
  5. A

    Analysing proportional data?

    Hi! I'm a masters psychology student needing a little help with a dataset I'm analysing :shakehead Dataset: My data has a within-subjects factor of time (i.e. first session vs last session) and a between-subjects factor of group (training vs control). One of my repeated measures DVs looks...
  6. B

    Normality question

    Hi everyone. I am doing a panel data project. One of the key factors is unemployment. The dependent is program enrollment. Unemployment is not normally distributed when I look at the normality plot. Does this make regression unreliable? There is a visible pattern when I look at the plot...
  7. J

    What would be the appropriate statistical tool?

    Dear all, I am a graduate researcher in the analysis phase of my research work. My research is an intervention research (n=14) trying to analyze the impact (pre and post) of the sports program. I don’t have a control group for this research. My dependent variables fall under ordinal, likert and...
  8. D

    how to obtain p-value from test statistic

    I am familiar with how to obtain the p-value from the t-statistic - the t-statistic is calculated by looking at the difference in means in two samples. Then, one has to integrate over a t-distribution from -t-statistic to +t-statistic and if the area under the curve is >0.95, then one can...
  9. I

    Falsify Normality results

    Is it possible to falsify normality results - in order to conduct parametric analysis of results? Or will someone be able to tell?
  10. Y

    Non-Normality - Measuring of stereotypes

    Hello :) I'm researching a moderated mediation (2x2) with two mediators. To test my MANOVA and moderated mediation I have to check the normality assumption of errors (residuals). My sample size is 400. 1.) One of my mediators has a non-normality distribution of residuals (which I think is...
  11. M

    Normality / QQ-Plot in Generalized Linear Models (GLM)

    Hi, sorry if this is a frequent question, but I did not find an appropriate answer: If I have a GLM with a non-normal distributed outcome (such as Poisson- or Binomial distributed), does it make sense to check normality of the residuals? Intuitively I would say no, since I explicitly...
  12. T

    parametric or non-parametric in comparison of a dependent variable within several gro

    down vote favorite I am comparing maths and chemistry scores of students in several schools. I am not comparing the schools with each other. I am just trying to say that students do better in maths than in chemistry in all of the schools studied. So I am comparing the maths and chemistry...
  13. B

    How to interpret original data after transformation to normality (discriminant analys

    Dear statisticians, Currently i am writing my thesis about business diagnosis. I got big list of companies with their financial data. These data are used to calculate financial ratio's like NITA (net income/total assets). I want to apply discriminant analysis (DA) on these financial ratio's...
  14. M

    normality problem

    I have 15 dependent variables on on IQ measure am using in my study but after checking for skewness and kurtosis two of them are not normally distributed.How can I justify this and go ahead to use parametric tests for my analysis
  15. I

    testing normality

    Can someone help to find the error in my code? I wanted to make a program in R which will tell me if a distribution is normal or not. It should also print a histogram with a density curve. After reading the .csv file and required packages (moments and ggplot2) i test my data for normality with...
  16. hanialbarni

    How can i check from this table if data normally distrubtion or not ?

    Hello How can I check from this output if data normally distribution or not ?
  17. M

    Testing the Normality of Errors in Regression?

    Hi all, I have simple conceptual question: In the simple linear regression problem, where the true relationship is, y = ax + b + e the error terms, e , are assumed to be normally distributed N(0,\sigma^2) . However, linear regression only yields estimates \alpha \approx a and \beta...
  18. L

    Partial spearman correlations and normality

    hello I am trying to conduct partial spearman rho correlations with syntax. However, I have different controls for my different variables. For example, with one variable I have 3 controls and another variable I have 5 controls. I am using the syntax from here...
  19. R

    Determining ideal sample size, testing normality in SPSS, bonferroni adjustment

    Hello all, I am new to the forum. I had a bit of training in statistics and research, particularly statistics in psychology, but I have some basic questions that are holding me back. I would appreciate the help. 1. How can I determine the ideal sample size for a study (upper and lower...
  20. S

    Justify the use of KS over Shapiro and Wilk normality test

    Hello there. I am testing my data distribution for normality using both Shapiro Wilk and Kolmogorov and Smirnov tests in SPSS. S&W reveals that the data is not normally distributed whereas K&S shows its approximately normally distributed. How can i justify the use of K&S over S&W in order to...