This shows the plot.

You can use the dialogue below the plot to download it chosing the name and the format of the plot

Thanks to Keith Newman for the download handler: shinyDownload

This shows all the data for the selected variable. Buttons at the bottom allow you to export the data.

This is ancient psychometrics but still of some use. For more information, see:

https://www.psyctc.org/Rblog/posts/2021-04-09-spearman-brown-formula

The formula is simple:

$$ \rho^{*}=\frac{n\rho}{1 + (n-1)\rho} $$

The short summary is that any multi-item measure will have overall internal reliability/consistency that is a function of the mean inter-item correlations and the number of items and, for any mean inter-item correlation, a longer measure will have a higher reliability. The formula for the relationship was published separately by both Spearman in 1910 and in the same year by Brown, who was working for Karl Pearson, who had a running feud with Spearman. See:

https://en.wikipedia.org/wiki/Spearman%E2%80%93Brown_prediction_formula#HistoryThat also gives some arguments that the formula should really be termed the Brown-Spearman formula, but I am bowing to historical precedent here.

App created 2.v.24 by Chris Evans PSYCTC.org

Last updated 2.v.24.

Licenced under a Creative Commons, Attribution Licence-ShareAlike Please respect that and put an acknowledgement and link back to here if re-using anything from here.

Background and related resources

This shiny app is one of a growing number in, my shiny serverThey complement:

- my Rblog of posts about using R
- the glossary linked with
- the OMbook
- the CECPfuns R package
- and it's all part of the resources of PSYCTC.org
- and linked with the CORE system web site

There is a form if you want to contact me: so do please use that if you think there is anything wrong here or anything that could be improved.

There is also now an Email announcement list, never updating more than monthly, where I will put up developments of new apps here, a summary of updates to the glossary and new posts in the Rblog. You can sign up for that here.