Chris Almaguer Data visualization design

Case study - 01 / Design systems & accessibility

Healthcare Design Systems

Executive dashboards for U.S. hospital systems. Each engagement asks a version of the same question: where do we rank against hospitals like us, and what do we do about it. Around six dashboards per client, about ten engagements, all of it built on a data visualization design system I created at Vizient.

Role

Sr. Designer, Data Intelligence & Visualization

Client

Vizient, U.S. hospital systems

Years

2022 to present

Tools

Figma, Power BI, Tableau

Surgical Value Optimization

Surgical Value Optimization. A spend view built on the system: service-line supply cost variation resolves from the left into procedure-level detail in the center, with the supporting literature in the rail. Sample data under the demo brand.

01 - The ask

Rank in the top percentile against hospitals like us

Hospitals do not come to us for a dashboard. They come with a goal: move into the top percentile of a cohort of comparable hospitals. The cohort is matched on size, case mix and type, so the comparison holds.

That framing decides everything downstream. A hospital already knows its own readmission rate. What it is buying is the ability to see that number sitting next to the hospitals it considers peers, and to find the service line where the gap is worth closing this year.

The engagement starts in a room. Executives, analysts, and the people who will actually open the file every Monday. We work out which measures the goal depends on, who reads them, and what decision each one is supposed to trigger. The output is a suite of around six dashboards on the client's BI platform.

I have run about ten of these. Six dashboards each is where the fifty comes from.

Wireframes

2 slides, wireframe stage
A wireframe slide titled Sectioning for data insights: three labeled tiers - key insights, drill-down analysis, root cause analysis - each tied by a leader line to a row of empty blocks.
Sectioning. Three tiers, top to bottom: key insights, then drill-down, then root cause. The layout gets argued as zones before a single component is drawn.
A wireframe slide titled Visual narrative structure and hierarchy: level one summary KPIs across the top row, supporting metrics beneath, drawn as empty blocks.
Visual narrative. Level one answers are we on track at a glance. Everything under it exists to explain that answer, which is what stops the top row from turning into a wall of tiles.

02 - Wireframing

Structure before color

I go back to square one on every engagement: boxes, greyscale, no styling. A palette cannot rescue a card that is answering the wrong question, and color arguments are much harder to have once someone has fallen in love with a layout.

Each component gets argued as structure. What is the reader looking at. What do they need beside it to trust it. What are they currently leaving the screen to find out.

Card anatomy

2 slides, card study
A study slide titled Key performance indicators. A single length-of-stay index card sits at the center, showing 1.08 against a 35th percentile pill, observed and expected values, encounter and long-stay counts, and a combined bar and trendline chart. Leader lines label every element of the card.
The card, annotated. Each element earns its place by closing a gap the reader would otherwise leave the screen to close: what was expected, how many encounters it rests on, where it sits against the cohort.
A study slide titled Interquartile interpretation. The same length-of-stay index card, with the chart replaced by a shaded band covering the middle fifty percent of peer performance, the hospital trend line running through it, and a highlighted marker on the latest reporting period.
Variation, not just position. The same card carrying the peer distribution behind it, so a reader can tell ordinary spread from a move that is worth acting on.

Designing the KPI card

The card exists to answer a comparative question, so every element on it is there to close a gap the reader would otherwise go somewhere else to close.

  • What is the number?
  • What was expected?
  • How many encounters is it based on?
  • Where does it sit against the cohort?

This is also where the KPI explainers get written. Case Mix Index and relative expected mortality are not self-evident, and a measure the reader cannot define is a measure they will not act on. The definition ships with the card.

The percentile indicator uses shape and a label, not hue alone. That is the accessibility rule showing up as a layout decision rather than as a color choice, which is the point of doing structure first.

The color study

5 slides, audit stage
A slide titled Applying color purposefully in data visualization: four palette types - categorical, sequential, diverging, and highlight against grey - each shown as a row of swatches.
Four jobs, four kinds of palette. Categorical, sequential, diverging, and a single accent against grey. Which ramp applies is decided by what the data is, not by what the brand owns.
A slide titled 60-30-10 rule: the brand orange and turquoise stepped down to 60, 30 and 10 percent tints, each block labeled with its hex value.
The brand palette at 60, 30 and 10. Orange and turquoise stepped down from full strength. The 100% tints are the ones a brand guide leads with, and the first ones the study rules out for data.
A slide titled Color distributions and WCAG compliance: a contrast table across seven tints, black text passing on every one, and the white-text rows struck through with a red cross.
Contrast at every step. Black text clears AA on all seven tints. White text fails on all seven, including the pairings the brand guide specifies. The crossed-out block is the finding, not a design flourish.
A slide titled Ensuring color accessibility for all users: the tested heatmap ramp and a red-yellow-green ramp, each shown again as a protanope and deuteranope would see it.
The same ramps under protanopia and deuteranopia. The tested ramp keeps its order. Red-yellow-green collapses into one olive run, which is why traffic-light coding does not survive the trip from a stoplight to a dashboard.
A slide titled Interpreting performance through color, comparing a continuous sequential ramp, a decile scale in ten equal steps, and a quantile scale cut at the top quartile and median.
Why quantile, not decile. Ten equal steps look precise and read as noise. Quantile buckets cut where people are actually judged - top quartile, median - so a performance tier is visible as a tier.

03 - Color, and the conversation about it

Why this ramp and not the brand one

Color is the touchy part of every engagement. It is the one design decision everybody has an opinion about, and it usually arrives attached to a brand guide that was drawn for a website.

So I stopped arriving with a preference and started arriving with evidence. I audited dashboards that were already shipping and tested the brand palette against three questions, in order.

01 / Does text stay readable at every tint?

Brand colors ship at 60%, 30% and 10%. Contrast had to hold at every step, not only at full strength.

02 / Do series stay distinguishable under color-vision deficiency?

All three types, at partial severity as well as full. Most people with a color-vision deficiency are not at 100%, so a standard built only for the extreme case fails the majority of the people it is for.

03 / Does it survive without color?

Greyscale printing and projector washout expose the same failure as CVD: color can no longer carry the information by itself.

Four rules came out of it, and they are the whole standard.

4.5:1
Text on any fill. AA contrast for body-size labels, checked at every tint step, not only at 100%.
3:1
Adjacent fills. Non-text contrast between neighboring segments, so a boundary holds without an extra stroke.
ΔE 10
Series separation. A minimum perceptual distance between any two series after CVD simulation.
5
Categorical ceiling. Past five series, color stops being a reliable encoding. Group, facet, or use position.

The conversation goes differently now. Nobody is being told their brand color does not work. They are being shown what it does at 30% behind a data label, and what the alternative is.

04 - Iteration and presentation

Four rounds, and what they are for

Everything goes through internal review before a client sees it. Then it gets presented, and typically runs four revision cycles.

The rounds are not cosmetic. Early ones argue about which measures earn a place on the top-level view, which is really an argument about what the executive team is accountable for. Later ones tighten labeling, defaults and filter behavior. By the fourth pass the changes are small, which is the signal that the structure underneath was right.

What makes four rounds possible rather than painful is that the rules are already written down. Revisions happen inside a standard instead of relitigating it.

A Figma canvas holding many dated versions of the same mortality dashboard, laid out in columns by revision round, with the file list of client pages down the left.
Four rounds, on the canvas. Every revision kept and dated beside the one it replaced, so a later round argues against a version still on screen rather than from memory.

05 - Development

Built, not handed over as a picture

The design work does not end at a Figma file. I work hand in hand with development through the build, in Power BI and Tableau, which is where a visualization standard either holds or quietly falls apart. Tools have their own defaults, their own color pickers, and their own opinions about what a chart should look like.

Being in the file myself is the only reliable way to find the parts of a design the tool cannot express, and to fix them before a developer inherits the problem.

What gets delivered

A 30-day readmissions and excess days dashboard on a MacBook: key indicators down the left, readmission patterns in the center, post-discharge pathways and outpatient revisits on the right.
Dashboard design sample; Key indicators on the left, the patterns behind them in the center, where the patients actually went on the right. Read across and the question resolves in that order: how big, what kind, and where. Great State Hospital System is a demo brand; every figure is synthetic.

06 - Handoff

What the room actually sees, and what they keep

Two things transfer at the end.

The first is the executive readout. It takes the measures that survived and puts them where a decision gets made, using the same ramps and the same rules, so a slide and a dashboard cannot disagree with each other in front of a board.

The second is the style guide. Hex values, the rule for when each applies, the KPI definitions, and components that already obey them. The client keeps building after we leave, and this is what decides whether what they build next still matches what we handed them.

07 - The system underneath

Why it repeats

None of the above would survive ten engagements as a personal habit. It survives because it is a Figma library: verified palettes as styles, chart components with the tints pre-applied, KPI card patterns, and annotation patterns for the cases where color alone is not enough.

Designers stopped picking colors for every chart. They picked a component, and compliance came with it. The accessible option became the fastest option, which is the only version of a standard that survives a deadline.

The library and the standard

2 slides, system stage
The design system open in Figma, its variables panel listing the colour token collection: brand tints, greys and the data-visualization ramps, each with a name and a hex value.
The library itself. The ramps are defined once and inherited throughout the system, so a change to the standard propagates instead of being reapplied by hand across fifty workbooks.
The color standard as a specification table. Rows for typography, data visualization ramps, pill indicators and wireframe components, each with a hex value, a color sample and a usage note.
The standard, written down. Diverging ramps at 60, 30 and 10 percent, pill indicators by decile, and wireframe greys, each documented with its hex value and the rule for when it applies. A ramp nobody can look up is a ramp that gets reinvented.