Tag: normality

237 Is normality testing 'essentially useless'? 2010-09-08T17:47:21.820

97 What if residuals are normally distributed, but y is not? 2011-06-23T06:00:00.923

89 Pearson's or Spearman's correlation with non-normal data 2010-10-19T01:14:16.967

47 Standard deviation of standard deviation 2010-07-26T16:10:45.817

47 Box-Cox like transformation for independent variables? 2012-09-05T10:37:28.063

43 Interpreting QQplot - Is there any rule of thumb to decide for non-normality? 2014-08-07T08:41:39.003

36 If the t-test and the ANOVA for two groups are equivalent, why aren't their assumptions equivalent? 2010-08-13T09:41:13.160

34 What references should be cited to support using 30 as a large enough sample size? 2010-09-10T17:07:39.130

34 How to perform a test using R to see if data follows normal distribution 2010-09-28T08:29:32.933

31 Normality of dependent variable = normality of residuals? 2013-05-30T05:36:29.133

30 What is normality? 2010-07-19T19:12:57.157

27 How incorrect is a regression model when assumptions are not met? 2015-12-29T22:42:51.127

24 Is it meaningful to test for normality with a very small sample size (e.g., n = 6)? 2011-08-08T11:06:04.043

24 Normalization vs. scaling 2012-09-03T08:56:19.270

23 What is the difference between the Shapiro-Wilk test of normality and the Kolmogorov-Smirnov test of normality? 2010-07-21T00:24:35.500

23 What should I check for normality: raw data or residuals? 2011-06-18T01:08:55.550

22 How robust is the independent samples t-test when the distributions of the samples are non-normal? 2012-10-09T00:29:25.453

21 How do I figure out what kind of distribution represents this data on ping response times? 2010-08-05T19:26:34.060

21 Interpretation of Shapiro-Wilk test 2011-09-17T12:18:37.520

19 Can we see shape of normal curve somewhere in nature? 2012-10-10T08:16:20.923

19 Example of distribution where large sample size is necessary for central limit theorem 2013-06-15T02:57:20.160

18 Appropriate normality tests for small samples 2010-08-13T12:42:30.220

18 Transformation to increase kurtosis and skewness of normal r.v 2012-11-13T10:51:17.607

18 Is Shapiro–Wilk the best normality test? Why might it be better than other tests like Anderson-Darling? 2014-03-20T11:09:46.973

17 How to test for differences between two group means when the data is not normally distributed? 2011-09-16T15:59:13.033

17 Assumptions of linear models and what to do if the residuals are not normally distributed 2014-05-27T16:23:40.353

15 Why do we assume that the error is normally distributed? 2012-02-09T13:34:26.007

14 Can I trust ANOVA results for a non-normally distributed DV? 2010-12-21T21:38:00.003

14 How does the sampling distribution of sample means approximate the population mean? 2013-01-15T22:14:21.763

13 Is there an explanation for why there are so many natural phenomena that follow normal distribution? 2016-03-30T04:39:03.417

11 What normality assumptions are required for an unpaired t-test? And when are they met? 2011-12-11T19:04:14.013

11 QQ plot does not match histogram 2013-03-14T15:30:50.447

11 Departure from normality assumption in ANOVA: is kurtosis or skewness more important? 2015-01-04T14:23:10.987

11 "Reversed" Shapiro–Wilk 2015-03-31T15:49:27.773

11 Why is F-test so sensitive for the assumption of normality? 2016-05-04T09:37:33.333

10 What other normalizing transformations are commonly used beyond the common ones like square root, log, etc.? 2010-08-12T13:20:13.170

10 Can I use a paired t-test when the samples are normally distributed but their difference is not? 2011-09-22T19:56:34.800

10 What is the expected distribution of residuals in a generalized linear model? 2013-04-24T09:05:12.410

10 Why does non-normally distributed errors compromise the validity of our significance statements? 2014-04-22T20:08:38.197

10 Why not always use bootstrap CIs? 2014-05-25T12:13:49.100

10 R: test normality of residuals of linear model - which residuals to use 2014-10-07T20:22:52.550

10 Repeated measures ANOVA: what is the normality assumption? 2015-05-10T19:50:23.203

9 Normal distribution and monotonic transformations 2010-07-27T13:49:41.073

9 Testing the normality assumption for repeated measures anova? (in R) 2011-01-08T11:26:07.737

9 What is a good index of the degree of violation of normality and what descriptive labels could be attached to that index? 2011-10-07T06:06:51.600

9 Assessing the power of a normality test (in R) 2013-10-29T17:53:42.027

9 Question about normality assumption of t-test 2015-03-11T14:52:25.707

9 Are any processes in nature distributed exactly normal? 2015-10-16T08:59:03.483

9 Normally distributed errors and the central limit theorem 2017-03-09T11:25:34.073

8 How to test for normality in a 2x2 ANOVA? 2012-05-03T06:22:14.790

8 Can I use a Z-score with skewed and non-normal data? 2012-07-16T01:54:16.880

8 Linear Discriminant Analysis and non-normally distributed data 2014-08-06T16:27:10.570

8 If my histogram shows a bell-shaped curve, can I say my data is normally distributed? 2014-12-17T05:00:50.787

7 Calculating the error of Bayes classifier analytically 2010-11-26T19:36:32.340

7 Bootstrapped parameter and fit estimates with non-normality for structural equation models 2011-04-30T06:10:14.923

7 Is there any test for a null hypothesis of non-normality? 2012-08-17T19:54:08.417

7 How to determine whether data is slightly or extremely non-normally distributed? 2012-08-30T05:12:19.663

7 Normality of residuals vs sample data; what about t-tests? 2012-12-11T14:58:42.830

7 Simple question about the asymptotics of estimators 2012-12-13T13:50:16.737

7 Regression - How do I know if my residuals are normally distributed? 2014-05-02T04:12:38.690

7 Why is a Pearson correlation of ranks valid despite normality assumption? 2014-07-01T22:18:25.723

7 Why is asymptotic normality important for an estimator? 2015-10-06T02:59:32.910

7 When is it OK to write "we assumed a normal distribution" of an empirical measurement? 2016-03-12T21:51:49.337

6 Testing normality 2011-06-23T05:23:12.733

6 Infinite p-value when checking normality of distribution 2011-06-23T09:32:09.913

6 Should the predictor variables be normally distributed for Poisson glm? 2013-04-25T19:56:42.830

6 Validity of normality assumption in the case of multiple independent data sets with small sample size 2013-06-03T10:01:20.760

6 Should I take the Shapiro Wilk test with a pinch of salt here? 2014-12-11T07:40:50.863

6 Distribution of "normalised" Gaussian random variables 2015-02-09T09:36:43.390

6 Heavy-tailed errors in mixed-effects model 2015-02-22T16:14:37.923

6 non-normal residuals in ARIMA 2015-03-23T21:04:57.297

6 Heteroskedasticity and Distribution of the Dependent Variable in Linear Models 2016-07-17T17:07:23.527

5 When should normalization never be used? 2010-07-27T15:56:38.297

5 Basic question regarding variance and stdev of a sample 2010-07-28T12:02:21.063

5 What is the normality test for binary data? 2010-10-12T12:34:08.707

5 Whether to report untransformed data when performing ANOVA on transformed data? 2011-11-28T16:48:15.317

5 Whether to leave the data unaltered in the face of outliers and non-normality when performing structural equation modelling? 2011-12-21T04:59:30.427

5 How to verify that simulated data is normally distributed? 2012-04-19T04:31:06.500

5 Is the sample variance a useful measure for non-normal data? 2012-08-01T11:01:03.807

5 What kinds of variables should we use the normality test for? 2012-08-23T05:49:21.440

5 Correlation and non-normal distributions 2012-09-27T08:05:49.183

5 How do you detect if a given dataset has multivariate normal distribution? 2012-10-28T02:51:18.030

5 Disagreement between normality tests and histogram graphs 2013-01-24T21:45:09.217

5 Student's t vs Mann-Whitney U for small equal samples 2013-06-27T06:05:10.587

5 Whether to test items for normality (and transform) when performing confirmatory factor analysis on a set of scales? 2013-10-03T06:11:18.640

5 Normality Testing - Choose the transformation that makes the data "most normal"? 2013-10-07T18:43:18.667

5 Panel data: OLS assumptions 2013-11-22T09:56:45.713

5 Does ARIMA require normally distributed errors or normally distributed input data? 2013-12-11T22:35:59.247

5 Proof that the log-likelihood is asymptotically quadratic 2014-01-05T14:25:21.567

5 Jarque-Bera normality test in R 2014-01-26T16:38:59.513

5 Testing large dataset for normality - how and is it reliable? 2014-04-03T10:49:43.107

5 Meaning of Qqnorm plot in R 2014-04-17T08:15:28.087

5 How can I determine if categorical data is normally distributed? 2014-12-17T04:07:31.480

5 A closed form formula for the normalizing constant in standard normal auto-regressive series? 2015-07-06T23:45:54.150

5 What is an example of data where the permutation test succeeds but a normal t-test fails? 2015-09-29T19:17:00.860

5 Why do statisticians prove asymptotic normality? 2015-11-27T00:47:24.777

5 Statistical tests for uneven groups 2016-03-09T11:46:23.967

4 Should quantitative predictors be transformed to be normally distributed? 2011-07-06T15:10:50.310

4 Multivariate normality test from R's energy 2011-07-14T12:44:44.703