# Plot in Action **[Irene de La Torre](https://observablehq.com/@irenedelatorre)** created the notebook **“[Comparing Placebo vs. Active treatments](https://observablehq.com/@irenedelatorre/comparing-placebo-vs-active-treatments?utm_campaign=plotpromo&utm_source=mail)”** to show the DLQI (Dermatology Life Quality Index), a measure of the quality of life for patients with different skin conditions such as psoriasis. [

](https://observablehq.com/@irenedelatorre/comparing-placebo-vs-active-treatments?utm_campaign=plotpromo&utm_source=mail) In the notebook, Irene describes some of the visualization techniques she used: _“I tried to strengthen the comparison between both treatments: instead of using opacity for describing the flow of patients, I used the stroke width of the lines. I also tried to be more descriptive around the items of DLQI.”_ See Irene’s example # #30DayChartChallenge The data visualization community is engaged in a [30 day chart challenge](https://observablehq.com/search?query=30daychartchallenge&utm_campaign=plotpromo&utm_source=newsletter), and several Observable users have created some great examples. Violeta Roizman is using Observable Plot to create a map of [all the trees in her hometown Buenos Aires](https://observablehq.com/@violetr/30daychartchallenge-day-4-flora); Shruti Mukhtyar is [faceting energy data](https://observablehq.com/@mukhtyar/day-3-historical); Advaith Venkatakrishnan is making [balls with basketball data](https://observablehq.com/@adv1996/april-2022-day-3-30daychartchallenge-historical); Tereza Iofciu is analyzing [gender diversity in the German Bundestag](https://observablehq.com/@terezaif/diversity-in-the-german-bundestag-2022), Adolfo Guimaraes is showing [who has internet access in Brazil](https://observablehq.com/@adolfoguimaraes/30daychartchallenge-day1), and more are coming every day. [

](https://observablehq.com/@violetr/30daychartchallenge-day-4-flora?utm_medium=newsletter&utm_campaign=plotpromo&utm_source=mail) _Violeta's map_ It’s not too late to join the challenge, which is open to everyone. Have fun trying out new techniques, and learn a few tricks along the way. The community is [here to help](https://talk.observablehq.com/) if you have questions or want to find a partner and collaborate on a chart. Check out the submissions! --- # Questions from the Community: Diverging bar chart and Likert scales In the Observable Forum, Eitan Lees [asked](https://talk.observablehq.com/t/diverging-stacked-bar-chart-in-plot/6028): *“I am interested in creating a diverging stacked bar chart to visualize some survey data. I have attached a sample notebook. What I would like to do is transform each bar to be aligned such that the “Neutral” category is centered on the x-axis about zero. I am using the [Robbins & Heiberger](http://www.asasrms.org/Proceedings/y2011/Files/300784_64164.pdf) paper as a reference.”* That is a _great_ way of asking a question, with a notebook, a dataset, and a scientific reference! When analyzing the answers to a survey, it is quite common to use a semantic differential (or Likert) scale, with answers being categorized as negative, others positive, and possibly a neutral option in the middle. In our answer, we focused on how to create a custom transform to implement this type of chart. This gave us an idea for [a new feature](https://github.com/observablehq/plot/pull/814) that is now available in the new version of Plot. Thank you, Eitan! If you have a question, please [visit the Forum](https://talk.observablehq.com/). [

](https://observablehq.com/@observablehq/plot-diverging-stacked-bar) See this example --- # A collection of 50+ Plot examples **[Plot Examples](https://observablehq.com/collection/@observablehq/plot-examples?utm_medium=newsletter&utm_campaign=plotpromo&utm_source=mail)** is a collection of 50+ real-world examples using Observable Plot. Curated from our team’s or many other Observable users’ notebooks, you will find grid choropleths, bump charts, plots of plots, COVID-19 timelines, rain clouds and UpSet charts, spine charts, ISOTYPE dot plots, and many more. And this is just the beginning! [

](https://observablehq.com/collection/@observablehq/plot-examples?utm_medium=newsletter&utm_campaign=plotpromo&utm_source=mail) Visit the Plot Examples collection --- # 30 Second Plot Video [

](https://youtu.be/t4grbTQJg30?utm_medium=newsletter&utm_campaign=plotpromo&utm_source=mail) Watch as we use Observable Plot to create a bar chart and add a filter using the "Select" Input, all in just 30 seconds! We've published [the notebook](https://observablehq.com/@observablehq/what-do-people-buy-on-bandcamp?utm_medium=newsletter&utm_campaign=plotpromo&utm_source=mail) featured in the video if you are interested. --- # Upcoming Events & Learning opportunities 📅 Join us on **April 26, 2pm PDT,** for the _Plot Happy Hour_! We'll have some examples prepared for you and will be answering your questions. [Sign up here!](https://www.meetup.com/observablehq/events/285156183/) *If you would like to host a future Observable Plot Meetup, please contact us at plot@observablehq.com* --- *This issue was edited by [Fil](https://observablehq.com/@fil), [Lauren](https://observablehq.com/@buchman), [Toph](https://observablehq.com/@tophtucker), [Dunstan](https://observablehq.com/@dunstan), and [Ian](https://observablehq.com/@enjalot). Please reach out to us by emailing plot@observablehq.com with your suggestions for the next issue.*