Becca Aaronson: "Visualizing Health Data," 7.23.15

Visualizing Health DataBecca Aaronson, The Texas Tribune

[email protected]@becca_aa

Accurate representation

As journalists, we have an obligation to ensure

that our stories — and visualizations — don’t

mislead or misinform our readers.

A good sourceThe source of your data — the entity, and individuals who collected, analyzed and published the data — must be reliable. And as a reporter, you must consider any bias that occurred during the collection, analysis or interpretation of the data, just as you would when considering a human source.

Census Data

Here’s how the U.S. Census categorizes “White” people:

“White. A person having origins in any of the original peoples of Europe, the Middle East, or North Africa. It includes people who indicate their race as ‘White’ or report entries such as Irish, German, Italian, Lebanese, Arab, Moroccan, or Caucasian.”

The “Lie Factor”

“Lie factor” = Size of the effect shown on the graphic / Size of the effect in the data

Every graphic’s “lie factor” should have a value between 0.95 and 1.05.

The “lie factor” should be between .95 to 1.05

This infographic has a “lie factor” of 2.8

Design variation

Changing the design of a graphic can confuse or mislead

readers, especially if graphics with varying designs are

side-by-side or not clearly labelled.

From Visualizing Health gallery

Tufte’s 6 principles:1. The representation of numbers, as physically measured on the surface of the

graphics itself, should be directly proportional to the numerical quantities

represented.

2. Clear, detailed, and thorough labeling should be used to defeat graphics distortion

and ambiguity.

3. Show data variation, not design variation.

4. In time-series displays of money, deflated and standardized units of monetary

measurement are nearly always better than nominal units.

5. The number of information-carrying dimensions depicted should not exceed the

number of dimensions in the data.6. Graphics must not quote data out of context.

The population mapWARNING: Don’t accidentally make a population map.

Here’s a good article on when maps shouldn’t be maps. And check out Darla Cameron’s 2015 NICAR lightning talk on alternative solutions.

Map: 2011 American Community Survey, poverty levels

By raw number...

By percent...

Politics of PreventionLet’s take a look at my fellowship project together, and the data visualizations created to support the series.

Map: Find Texas Remaining Abortion Clinics

How much is a limb worth?ProPublica’s “How Much is a Limb Worth?” is amazing for many reasons, particularly how they visualized the data. Let’s watch this short clip on Scott Klein and Lena Groeger explaining how they built it.

Stories + Graphics

Example 1

Example 2

Build your ownDatawrapper.de — Built by Danish journalists

Chartbuilder — Built by Quartz

Los Angeles childrenLet’s say you’re working on a story about poverty impacts children with disabilities living in the Los Angeles area. According to 2013 American Community Survey data, a greater proportion of Los Angeles children with disabilities have incomes below the federal poverty level in the past 12-months.

Let’s visualize it!

1. Go to Chartbuilder. Click “Chart grid” in Step 1, then delete the default data in Step 2.

2. Open this spreadsheet.3. Copy the data on the worksheet “Under 18 -

Poverty Level”4. Paste your data in Step 2.

So far, it should look like this.

5. Under Step 3, select 2 rows and 1 column.

6. You still need to label the data. On Step 4, add “%” or “ percent” as a suffix

7. Add a title and source information on Step 5.

8. Download your image, and you’re ready to go.

Let’s take a step back...The data you just copy/pasted was cleaned up from American Community Survey data. Let’s go through how we got the data ready for presentation.

Get the data● Download the raw data or view the original data on our street on

the Worksheet labelled “ACS_13_1YR_B18130_with_ann.” The fields we want to use are highlighted in blue.

● Copy all of the columns from the first blue column to the last blue column — HD01_VD02 to HD01_VD15. In your own spreadsheet, create a new worksheet titled “Data fields.” Right click on cell A1 and select “Paste special > Paste transpose.”

● Put your cursor on B1, click the arrow on the top right corner, and select “Sort Sheet A-Z”

Here’s a screenshot of the worksheet “Data Fields,” which includes the information we want to analyze to see how many Los Angeles children with disabilities are also below poverty level, compared to children without disabilities.

Next, we want to add the children “Under 5 Years” and “5-17 Years” by disability and income status to get an estimate for all children in each of the sub-groups. Create a new worksheet titled “Calculations” and set up the following structure:

Now, copy the data you’ll be working with and paste it underneath. For ease of reference, I’ve just brought over the 4 data fields we need to add together, and organized them by age group. You can bring over all of your data, but make sure to widen the header on the data description column, so that you can double-check you’re referencing the correct fields.

Sum the two age groups with corresponding disability and income status to fill in your spreadsheet:

Next, calculate what percent of children with disabilities fall into each income range. Then do the same for children with no disabilities.

Now you’re ready to chart!Let’s try another charting tool, Datawrapper.de

Open the website, select “+New Chart” in the upper right corner. You can copy/paste the estimated totals that we just calculated. If you have a large dataset, you can also save it as a .csv and upload the file.

Click on a column header to change the format, add prefixes or suffixes (like ‘$’ or ‘%’) or hide a column of data from the visualization.

Test different layoutsSee what the data looks like as a “bar chart” or “column chart” and other views.

Click on “2 Check & Refine” to go back a step. On the top left corner of your data table, click “Transpose,” then “Proceed.” Now look at the various chart types. Notice a difference?

Prepare to publishClick “Refine” to choose different colors for your chart. Click “Annotate” to add a title and source information about your data.

When you’re ready, hit “Publish.” You’ll need an account to save your graphic.