published on 10.11.2018

SD vs SEM

While the mean and standard deviation are descriptive statistics, the mean and standard error describes bounds for a random sampling process. This difference changes the meaning of what is being reported: a description of variation in measurements vs a statement of uncertainty around the estimate of the mean.

In other words standard error shows how close your sample mean is to the population mean. Standard deviation shows how much individuals within the same sample differ from the sample mean. This also means that standard error should decrease if the sample size increases, as the estimate of the population mean improves. Standard deviation will not be affected by sample size.

Gregory Verleysen, ResearchGate

The SD indicates the dispersion of individual data values around their mean, and should be given any time we report data. The SE is an index of the variability of the means that would be expected if the study were exactly replicated a large number of times. By itself,this measure doesn’t convey much useful information. Its main function is to help construct 95% and 99% CIs, which can supplement statistical significance testing and indicate the range within which the true mean or difference between means maybe found.

Maintaning Standards: Differences between the Standard Deviation and Standard Error, and When to Use Each


The Standard Deviation of the means is called The Standard Error.

Standard deviaton, tells us how the data is distributed around the mean. Standard error, tells us how the mean is distributed. Confidence Intervals are related to standard errors. Since we are trying to interpret the confidence interval of the average value. We are considering how averages (means) are distributed.

Skewness & Kurtosis

What’s the acceptable range of skewness and kurtosis ?

-2 +2 are usually fine.

(Trochim & Donnelly, 2006; Field, 2000 & 2009; Gravetter & Wallnau, 2014) (George & Mallery, 2010) SPSS for Windows Step by Step: A Simple Guide and Reference, 17.0 update (10a ed.)

It depends on mainly the sample size. Most software packages that compute the skewness and kurtosis, also compute their standard error. Both S = skewness/SE(skewness) and K = kurtosis/SE(kurtosis) are, under the null hypothesis of normality, roughly standard normal distributed. Thus, when |S| > 1.96 the skewness is significantly (alpha=5%) different from zero; the same for |K| > 1.96 and the kurtosis.

Source: Casper J Albers

How to compute SE of skewsness and SE of kurtosis? Roughly,

SE(skewness) = SQRT(6/N) 
SE(kurtosis) = SQRT(24/N)
Published on 10.11.2018 by Mert Bakır with commit 7dfab23.
statistics
#math #statistics
published on 10.07.2022

Previously, I’ve published a blog post about deploying static content on heroku with basic authentication. You can find the link here. In that post, we hosted the source code on GitLab and configured a CI/CD pipeline to render the static content a.k.a html files and push these files to Heroku. …

published on 28.05.2022

Each git commit has a field called Author which consists ‘user.name’ and ‘user.email’. We usually set these variables once, after installing git, with git config --global so that each repo gets the variables from the global definition. We can also set them locally for a …

published on 25.05.2022

In this post, I’ll first walk through hosting static content with basic authentication. Then, we’ll look into deploying to Heroku using GitLab Pipelines, more specifically deploying a certain sub-directory within the project instead of pushing the whole project. Also, I’ll share …

published on 17.04.2022
edited on 15.07.2022

Önceki bölümde, markdown formatını LaTeX formatına dönüştürmek için kullanılan Pandoc yazılımından bahsetmiştik. Şimdi konuyu bir adım daha ileri taşıyıp ve bookdown’a geçiyoruz. Bookdown; Rmarkdown kullanarak teknik dökümanlar, kitaplar yazabilmemizi sağlayan, Yihui Xie tarafından yazılmış …

published on 10.04.2022

I’ve been using WSL-2 on Windows for over a year. It’s very useful because some Python packages are just a headache to install on Windows. Also, docker. It’s just better on Linux. Yet, WSL-2 can also be problematic. I remember trying a dual-boot setup when things just went way too …

published on 03.03.2022

In this post, I’ll share how to install geopandas and some other gis related packages on Windows. If you are on Mac or Linux you can probably just pip install those without any issue. I usually had to do a google search every time I wanted to install these packages on Windows environment. Of …