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Service Design 2025 Mixed Methods

Reducing Wait Times
at Solid State Coffee

I utilized a mixed methods approach — quantitative data to source baselines and qualitative data to inform insights — which led to a full service design undertaking spanning end-to-end research, design, and implementation.

Role

UX Researcher &
Service Designer

Timeline

May–Nov 2025

Methods

Quantitative Analysis Contextual Inquiry Semi-Structured Interviews

Deliverables

Research Report Service Flow Map Service Design Blueprint Employee Break Schedule

01 · The Challenge

A reputation problem
hiding in plain sight

13:37

Average weekend wait — vs. 5 min Starbucks benchmark

Solid State is a specialty coffee shop and café on the Upper West Side. Founded in 2021, the shop had built a loyal following through exceptional coffee and a full kitchen program. By 2025, staff had noticed customers glancing at the line and walking away — but how often this was happening, and why, remained unknown. No baseline data existed.

The bar manager approached me as a friend and asked if I had any ideas for changes. Before jumping to solutions I wanted to have better clarity on what exactly was happening in the service flow and knew that research would be a necessary first step.

Solid State Coffee interior — counter and service space

02 · Research Approach

Three simultaneous studies

⊙

Quantitative Study

Wait Time Analysis

Ten volunteer secret shoppers collected ~60 data points over one month during peak hours between 9am and noon. Each tracked total wait time, time to the register, and time from ordering to drink delivery — providing the first factual baseline for the cafe.

10 shoppers ~60 data points
◎

Qualitative Study

Contextual Inquiry

Approximately 20 sessions of naturalistic observation and 10 interview-plus-immersion sessions working behind the counter alongside baristas. I watched how each workstation fit into the service flow, how equipment positioning shaped behavior, and followed up on observations with staff interviews in real time.

~20 observations 10 immersions
≡

Qualitative Study

Semi-Structured Interviews

Ten semi-structured interviews with participants recruited from around the neighborhood at other coffee shops — not inside Solid State — to avoid sampling bias toward high-affinity customers. Probed for how people experienced and responded to wait times and what drove decisions about where to go for coffee.

10 participants Semi-structured

In the field

Working behind the counter, not just watching from it

The contextual inquiry involved working alongside baristas during peak hours — not as an outside observer but as someone embedded in the flow. That proximity surfaced details that observation alone would have missed: where staff hesitated, which handoffs created friction, and how the physical layout shaped decisions in real time.

Working behind the counter at Solid State to analyze the service flow

03 · Key Findings

A single overtasked register was
the bottleneck for the entire experience.

Average wait time, in minutes
0:00 3:00 6:00 9:00 12:00 15:00 18:00 Wait time 4:14 3:19 7:33 8:13 3:12 11:25 8:37 6:05 14:42 7:52 4:51 12:43 Mon–Thu Friday Saturday Sunday
Wait to order
Wait for drink
Total wait time, in minutes
0:00 3:00 6:00 9:00 12:00 15:00 18:00 Wait time 8:17 11:35 17:11 17:37 6:42 11:16 12:05 6:44 7:33 11:25 14:42 12:43 Mon–Thu Friday Saturday Sunday
Wait time range
Average wait time

Findings, in priority order

01

The register was the primary bottleneck

The register workstation had accumulated 6+ distinct task types simultaneously during peak hours — order taking, payment, menu questions, food delivery, drink service, and pickup management — because it was never redistributed as staff and customer volume expanded. At peak, a single complex order could hold up a queue of 10 to 15 people behind it.

Operational Design Workstation Structure

02

Wait times were long enough to pose a reputational risk

Weekday waits averaged 8:13 and weekends 13:37 — well outside Starbucks' reported 5-minute benchmark. A customer who recommends Solid State almost always adds "but be prepared to wait awhile." That caveat, repeated enough times, becomes the shop's identity.

"It's the best coffee on the Upper West Side. I just don't go on weekends anymore."

— Neighborhood Interview Participant

"All ten participants mentioned the line in their interview — with five of the ten saying they would never visit Solid State on weekends because of it. Four of the ten stated it was great coffee, if you can wait for it."

— Neighborhood interview synthesis

Reputational Risk Customer Behavior

03

Two customer types were moving through a flow designed for neither

To-go orders typically cleared the register in under 2 minutes. Dine-in orders with food regularly took 2 to 6 minutes, often involving allergy questions, ingredient specifics, and multi-item specifications. Both moved through the same line and the same register, with no mechanism to distinguish them — meaning a single complex order stalled every quick transaction behind it.

Service Flow Customer Segmentation

Order time per customer

Flow A

To-go customers

< 2 min

Single drink, fast transaction, in-and-out. Cleared the register quickly when the queue allowed.

Flow B

Dine-in customers

2–6 min

Multi-item food orders, allergy and ingredient questions, menu specifications.

Recommendations · prioritized by effort to impact

Two high-impact interventions emerged directly from the findings

01 · High Impact

Strip the register back to a single function

Redistribute non-ordering tasks to other workstations, simplifying the register's responsibilities to order taking and menu discussion. Create an additional workstation to absorb pickup and delivery, with a second supporting role between the order queue and dine-in service.

02 · High Impact

Create separate entry points

Build a true split between to-go and dine-in customers — either through QR ordering for dine-in only with the register reserved for to-go, or by adding a second physical register to create two parallel entry points. Either path moves complex, multi-item orders out of the main queue entirely.

Service flow — before & after redesign

Restaurant flow current — complex service flow diagram showing the existing ordering process

Current flow — before redesign

This diagram maps every step a customer and staff member move through under the original service model. All interactions — order taking, payment, menu questions, food delivery, and pickup — funnel through a single register workstation. At peak hours, one complex dine-in order can stall the entire queue behind it, causing the 13-minute average wait times captured in the quantitative study.

Restaurant weekday flow revised — streamlined service flow diagram

Revised weekday flow — after redesign

The revised weekday flow separates to-go and dine-in pathways at the point of entry. Tasks previously stacked at the register are redistributed across dedicated workstations, and complex multi-item orders move through a parallel track rather than blocking the main queue. The result is a significantly shorter and more legible flow for both customers and staff.

04 · Impact & Outcomes

From cost-cutting
to evidence-led decisions

Before the research, operational decisions at Solid State were driven primarily by a lean cost-reduction mindset — staffing and inventory kept as tight as possible. The café had outgrown that framework, but the service flow had never been adapted to reflect the increase in staff or customers.

Organizational Action

Findings translated into role shifts before redesign

After the research surfaced several insights about the service design, the team recognized that they didn't have a structured system to receive feedback or catalog changes. They also recognized that certain team members were responsible for tasks that were not best suited for their skills and preferences. So, a re-assignment of responsibilities happened within the organization based on the research insights and my influence through asking pointed questions through the contextual inquiry.

Cultural Shift

From change-resistant to design-curious

With the new infrastructure in place, the impact on the team went beyond physical changes. Staff members who had previously been resistant to change began making design recommendations unprompted, and on multiple occasions asked me to either run additional research on something they had observed or to redesign other aspects of the café.

Ongoing · Measurement

Orders taken per hour

Implementation is ongoing. The primary metric I'm tracking is orders taken per hour during peak hours. Once throughput data is in, I'll pair it with customer satisfaction data to get a complete picture of whether dual entry point system is working as intended.

Research artifacts — service blueprints

Service blueprint current state — front-stage and back-stage task mapping

Task-oriented blueprint — front-stage and back-stage actions mapped across the customer journey

Full service blueprint with floor plan showing customer journey and recommended staff touchpoint changes

Spatial blueprint — customer journey mapped onto the physical floor plan with recommended workstation redistribution

05 · Reflection

What I would
do differently

"Stakeholder management isn't adjacent to research work — it is research work."

If I could go back, I would shift my initial strategy to include more quantitative methods to better assess the baseline. Methods like neighborhood-focused surveys and competitive analysis of nearby coffee shops might have provided more relevant benchmarks to compare against. When I started this project I was very focused on practicing qualitative skills; more recently, I've taken a quantitative methods course to better utilize quantitative data in the future.

Further, I realized the hardest part wasn't the research itself — it was navigating a team cautious about change. Learning to roll with resistance, understand what each person's goals were within the organization, and earn trust before pushing for change: all of these are motivational interviewing concepts I thought I had left behind in mental health counseling, but it turns out they are equally relevant in stakeholder management. I now understand that stakeholder management isn't adjacent to research work; it is research work.

I started this project underselling my own contributions, but what I learned is that this kind of work — surfacing what leadership couldn't see, reframing a general "how do we go faster" question into a specific structural redesign — can change teams, systems, and culture in ways that go well beyond the original brief. That has fundamentally changed how I see what research can do.

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Contact Information

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thornton.coen@gmail.com

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