Linked Questions

0
votes
0answers
25 views

Sample size calculation for parametric test, with large effect expected, small numbers. Should I use parametric or non parametric tests?

I am trying to figure out what would be the best way to analyze data from a randomized double blind trial we conducted. We sought to find if two dosages of a drug were effective for a severe symptom ...
0
votes
0answers
56 views

How to verify assumptions of a normal distribution? [duplicate]

I'm working with the iris data.I made a density plot And a qq plot For sepal Length.It looks Approximately normal With the left skew And a flat peak The points In the qq Plot Stay within The ...
0
votes
0answers
56 views

Non-parametric analysis for between-subjects

I performed 3 experiments, each experiment tested a different system, and each experiment involved a distinct group of subjects. In total there where 25 participants (7 for the first system, 7 for the ...
0
votes
0answers
54 views

What criteria to use for goodness-of-fit test for normal distribution ?

There are several goodness of fit tests, may be chi-squared is most famous one, however it seems it is not a preferable choice to be used in the case of continous variables. There is an excellent ...
0
votes
0answers
23 views

Comparison of unbalanced groups of values

I know there are several questions (here and on other websites) regarding the comparison of values, but I am still lost with the data I have and the analyses I should conduct. I have just 18 values (...
0
votes
0answers
38 views

If the data is not normally distributed and the skewness is = 0.208 SE of skewness is 0.144 , is it acceptable to use t-test? [duplicate]

The sample size is 288 and by Shapiro- Wilk test the data is not normally distributed.
0
votes
0answers
495 views

Time series- log returns statistics, test normality

I downloaded data from yahoo to study all the statistics of the time series. I then calculated the returns by using: $Ln(\frac{S_t}{S_{t}-1})$ using the adj close price in the following excel file: ...
0
votes
0answers
580 views

Normally distributed data but small sample size, use nonparametric test?

My data set is very small (n=16) which according to a Shapiro-wilk test is normally distributed (p=0.82), despite the histogram looking questionable. When I split the data into my two categories there ...
0
votes
0answers
258 views

What is the best way to test normality for a very large sample size 15000? [duplicate]

Also do I need to test the normality for the categorical data? Thanks
0
votes
0answers
609 views

Normality assumption in MANOVA

Data set has 2 dependent variables and 1 independent variable with 3 groups. Normality assumption of MANOVA says that variables has to be normally distributed within the groups. My data set has 30 ...
0
votes
0answers
217 views

how to construct the likelihood if my errors are not Gaussian

My aim is to study the correlation between 2 parameters knowing that I have measurement errors in both parameters, i.e. I have uncertainties on the independent and dependent parameters. I want to ...
0
votes
0answers
33 views

When compare a variable in different times, one has normal distribution, another doesn't, which test should I use?

The question is to compare means of sales volume in different periods. So I got sales period 1 and sales period 2. Sample size is 40. The skewness, kurtosis, test of normality and histogram all show ...
0
votes
0answers
72 views

Normality test with p-value equal to zero [duplicate]

I have an array dataset of about 650.000 points. I want to test if the dataset follow a normal distribution or any other distribution. The first thing I did was to split the data in groups, find the ...
0
votes
0answers
134 views

Are very low ANOVA and Kruskal Wallis p-values reason to doubt the results?

I have four relatively small sets of data under five different conditions. For each set of data I want to see whether the differences between the conditions are statistically significant. The first ...
0
votes
0answers
924 views

Why do some researchers test for normality of sample data?

I once was a research assistant for a professor who wanted me to do some regressions, but before that he wanted me to test all the sample data for the variables to ensure they were normally ...

15 30 50 per page