# Questions tagged [shapiro-wilk-test]

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### What test is appropriate for normality of continuos data grouped in bins

I have a data set of continuous data. From 1000 observations, the resulting dataset is only 29 rows and two columns: the range (starting point) and the count. Pearson - Weldon crabs dataset range ...
2k views

### Why is my data not normally distributed while I have an almost perfect QQ plot and histogram?

I am doing a thesis and I am stuck with my statistics on time series data. And when I run a Shapiro test, or any test, it says: ...
18 views

### Test for gaussian mixture fit when component assignment is known?

I have a process 𝑃 generating random variables X_1, ... X_n. From each of these I've sampled a set of samples ...
348 views

### QQ plot result doesn't correspond to normality test [duplicate]

I am considering an ANOVA model for such data: ...
1 vote
40 views

### Statistical analysis - Shapiro-Wilk test?

I apologize if this question will seem odd, but I am quite new to statistical analysis. I performed coinfection experiments with a total of 12 conditions, and I have 3 measurements per condition. I ...
1 vote
37 views

### R: Shapiro-Wilk test yields different results in descriptives and in One-Way ANOVA

I got a dataset of 60 people from a between-subject approach that I was trying to check for normality. (Since I need information about normality for ANOVA post-hoc tests.) They were split in three ...
1 vote
53 views

### Shapiro Wilk test of normality

I ran my data under JASP and the p-value for the shapiro wilk test of normality was <.001. How do I interpret this?
66 views

### How to transform a set of negative values to obtain a normal distribution? [duplicate]

I am having quite a few problems with transforming a set of data with values between -1 and 0, as I need to normalise them. I tried to use the following formulae: [(𝑥−min(𝑥))/(max(𝑥)−min(𝑥))] AND ...
1 vote
26 views

### Is there a way to calculate peaks of a distribution mathematically?

I’m trying to find some way to mathematically calculate the number of peaks in a distribution. I know there are various tests (such as Shapiro Wilk) that assess whether a distribution is normal, but I’...
31 views

### Two-Way anova assumptions not fulfilled

My task is to determine whether two different categorical variables (residence location (city/rural) & residence size (small/medium/large)) have a connection on one numeric variable (residence ...
35 views

### if I have a variable in my data that is not normally distributed, could I still use an ANOVA if my sample size is large enough?

I have a sample size that is more than 30 but one of my continuous variables is not normally distributed. The Shapiro-Willk test does say that my data is not normally distributed. I am going to ...
19 views

### Small Sample - Confidence Interval Mean

I have a sample size of 14 and I plan to measure confidence intervals for the mean of different characteristics. I can say this about my data: ...
45 views

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### Limitations of Shapiro test

Are there any possible limitations to the Shapiro test or the shapiro.test() function? After removing outliers in a data set it seem that using the ...
1 vote
235 views

### Compare Z-scores (weight) before / after with a T-test?

I'd like to ask you if it's possible to perform a T test to calculate Z-scores ( weight of persons ) https://www.cdc.gov/growthcharts/clinical_charts.htm with a t test in the same group ( paired t ...
44 views

### Reasoning for tranforming linear model to log-level

I have a multiple linear regression model and found that my error terms are not normally distributed. When looking at the histogram of the dependent variable, it looks like below. I am not sure how ...
181 views

### Understanding the Shapiro-Wilk normality test

I am trying to learn how to check if the distribution of values in a set is normal or not. Making a histogram and a boxplot shows: Performing the hapiro-Wilk normality test I get: ...
35 views

### My normality plot and Shapiro's test say different things

I have an LMER, and I want to check for normality; my plots show this: However, my shapiro test shows this: ...
616 views

### Performing a shapiro-wilk test on residuals from an LMER and repeated-measures ANOVA

I would like to perform a Shapiro-Wilk test on my data which takes the form of an LMER. The LMER model is named lmerabsolute. ...
11k views

### Can a sample larger than 5,000 data points be tested for normality using shapiro.test by applying the test to a subsample?

I have a number of samples that I would like to test for normality. One of the samples exceeds 5,000 data points, the limit up to which the shapiro test accepts samples. This is the data: ...
176 views

### Alternatives to Pearson's correlation given small sample size and normality hypothesis rejected?

I would like to use Pearson's $r$ to determine the correlation strengths among around $20$ variables. Unfortunately, I had to reject the hypotheses that the data from some (around $5$) comes from ...
66 views

### Checking the normality of a large sample?

If I want to analyze a large sample size (N = 50.000) of continuous data (\$ revenue) from an A/B test, what would then be the best way to check for normality? Thanks in advance!
2k views

### If a sample is not normally distributed, can a subset of the sample be normal?

I have used a Shapiro-wilk test on all of my data and the results show that it is not normally distributed. However, could this mean that a subset of my data could still be normally distributed?