Trent Turner
Case study 04 / Independent Analytical Work

Visual Analytics & Data Storytelling

Interactive dashboards and supporting analyses that make evidence useful for decisions.

The interactive dashboard is the primary example: I designed its information architecture, KPI structure, filters, and visual communication to help readers explore evidence and its limitations. Independent statistical and exploratory projects below show the analytical reasoning behind those communication choices.

My Role
I developed the analyses and visualizations and interpreted their findings.
Business / Analytical Question
Which comparisons reveal useful evidence, and which apparent findings need qualification?
Evidence
An interactive North Carolina turnout and public-opinion dashboard, with supporting model diagnostics, polling comparisons, and cross-country studies.
Decision / Finding
Use appropriate benchmarks, organize comparable evidence, and distinguish association from causation.
Outcome / Status
Independent analytical work. Model validation and source limitations remain explicit; no client deployment or business lift is claimed.
01 / Interactive decision support

North Carolina turnout & public opinion

An interactive dashboard for exploring statewide turnout, demographic and county patterns, and public opinion. It brings high-level indicators and detailed comparisons into one analytical experience.

I designed the information hierarchy, KPI structure, visualizations, filters, and interactions to help non-technical readers move from an initial signal to the context needed to interpret it—without working through raw datasets.

Open the full report to use its navigation, filters, and detailed views.

Open full dashboard (opens in a new tab)
Information hierarchy
Statewide indicators establish the overview before separate views introduce demographic, county, and public-opinion detail.
Interaction
Report navigation and survey filters let readers change the analytical lens and compare topics, populations, and pollsters within one experience.
Visual selection
Trends, composition, geographic comparisons, and response distributions use visual forms suited to the question. Tables retain the source and survey context needed to interpret them.
Communication
Clear labels, consistent formatting, and visible source notes help non-technical readers find the takeaway while keeping definitions and limitations available for deeper exploration.

Independent analytical work, not a professional client deployment. Turnout and public-opinion comparisons require attention to source dates, population definitions, survey methods, and uncertainty; the report’s methodology provides that context. These public-data views do not report proprietary business acquisitions.

02 / Statistical reasoning

High accuracy concealed poor discrimination

Question
Does approximately 79% accuracy establish useful classification performance?
Approach
Compare logistic-model testing accuracy with a majority-class reference and inspect ROC-AUC. The source dataset contains 26,570 observations: 20,921 successful outcomes and 5,649 failures.

High accuracy concealed poor discrimination

Model test accuracy
≈79%
Majority-class reference
≈78.7%
Accuracy scale: 0–100%. The majority-class reference uses the full dataset, not the model test partition.

Discrimination remained below the chance reference

0.5 chance reference

ROC-AUC ≈0.393 · Scale 0–1

Source: original logistic-model testing results. Review positive-class coding and probability direction before operational interpretation.
Finding
The headline accuracy initially appeared strong, but the majority-class reference produced nearly the same result. ROC-AUC provided additional evidence of weak discriminatory power.
Interpretation
Accuracy alone was a misleading evaluation metric for this class distribution. The reference and test set cover different populations; this comparison is diagnostic, not a reproduced test-set benchmark. Review class coding and probability direction, then validate further before operational use.
View chart data and original analysis
Original model evaluation and dataset reference
MeasureValuePopulation
Accuracy0.7892756Testing
ROC-AUC0.3925843Testing
Accuracy0.7895084Training
ROC-AUC0.3976502Training
Majority-class reference20,921 ÷ 26,570 ≈78.7%Full dataset
Original logistic ROC analysis.
Original logistic ROC analysis. View full size ↗
Original class distribution.
Original class distribution. View full size ↗
Missing-value screening across predictors.
Missing-value screening across predictors. View full size ↗
Exploratory predictor and product-group comparisons.
Exploratory predictor and product-group comparisons. View full size ↗
Decision-tree structure and feature importance. Importance alone does not establish predictive reliability.
Decision-tree structure and feature importance. Importance alone does not establish predictive reliability. View full size ↗
03 / Exploratory analysis

Compare the distribution before explaining the difference

Question
How do polling percentages and observation totals vary across pollster groups?
Approach
Compare the distribution of reported percentages, then inspect aggregate observations to identify questions about comparability.

Polling spread differs across groups

Original plotted percentages and axes, isolated from the legacy dashboard. Groups use the source’s “Top 4 Pollsters” definition.
Original plotted percentages and axes, isolated from the legacy dashboard. Groups use the source’s “Top 4 Pollsters” definition. View full size ↗

Observation totals provide context

Original aggregate observation totals. Totals are not a measure of poll quality.
Original aggregate observation totals. Totals are not a measure of poll quality. View full size ↗
Finding
The original exhibit shows a wider spread among the other pollsters alongside smaller aggregate observation totals.
Interpretation
The comparison identifies a question to investigate; it does not establish that sample size caused the difference. Timing, population, weighting, and methodology must be comparable before interpreting group differences.

Source: original public-opinion visualization. Underlying poll-level rows are not available with these exports. Plot marks are preserved rather than reconstructed from estimated values.

04 / Evidence-based communication

Relationships require careful interpretation

Question
Which factors were most strongly associated with reported happiness?
Approach
Inspect country-level scatterplots of happiness against corruption perceptions and GDP per capita, using the original fitted lines as visual context.

Governance perceptions and happiness

Corruption Perception Index and average happiness score. Original axes, points, fitted line, and null indicator preserved.
Corruption Perception Index and average happiness score. Original axes, points, fitted line, and null indicator preserved. View full size ↗

Income and happiness

GDP per capita and average happiness score. Original axes, points, fitted line, and null indicator preserved.
GDP per capita and average happiness score. Original axes, points, fitted line, and null indicator preserved. View full size ↗
Finding
Both views show observed relationships. The original visual interpretation emphasized the governance-perception relationship.
Interpretation
These observational plots cannot identify causal effects. Without underlying rows, correlation coefficients, or fit diagnostics, the exhibits do not establish a newly validated ranking of relationship strength. Each scatterplot displays 129 nulls; missingness requires review before stronger conclusions.

Source: original cross-country happiness analysis. Portfolio views preserve the plotted evidence and replace the legacy causal headline with association-based framing.

View geographic and country comparisons
Original geography of average happiness scores. Source legend and map attribution preserved.
Original geography of average happiness scores. Source legend and map attribution preserved. View full size ↗
Original country comparison of happiness, corruption perception, and GDP per capita. Different measures retain their own axes; bar lengths are not comparable across panels.
Original country comparison of happiness, corruption perception, and GDP per capita. Different measures retain their own axes; bar lengths are not comparable across panels. View full size ↗
Analytical range

Operational and geographic comparisons

These independent examples apply the same question → evidence → interpretation structure to different visual forms.

Staffing, customers, and satisfaction
Question
How did customer volume and satisfaction change alongside staffing levels?
Approach
Compare changes in customer volume across periods, then assess whether the evidence supports a staffing explanation.

January customer volume relative to the first year

January Y1
100.0
January Y2
62.3
Calculated index: January Y1 = 100. Raw customer counts and the source timeline are withheld.
Finding
Customer volume and the gap between total and satisfied customers varied across staffing periods.
Interpretation
The timing supports further investigation of service capacity. It does not isolate a staffing effect or establish that staffing changes caused changes in customers or satisfaction.
Facilities-cost forecasting
Question
How might facilities costs develop beyond the observed period?
Approach
Use a time-series visualization to separate observed costs from the forecast.
Original facilities-cost forecast and comparison dashboard.
Original facilities-cost forecast and comparison dashboard. View full size ↗
Finding
The exhibit makes the projected trajectory and its uncertainty visible.
Interpretation
A forecast is a conditional estimate. This export does not provide forward-validation metrics or evidence of an operational deployment.
Geographic wage comparison
Question
Where do wage levels differ geographically in the source exhibit?
Approach
Use a geographic visualization to reveal regional patterns.
Original geographic wage comparison; historical analytical exhibit, not a current wage reference.
Original geographic wage comparison; historical analytical exhibit, not a current wage reference. View full size ↗
Finding
The map highlights geographic differences for further investigation.
Interpretation
Geographic patterns alone do not explain their causes. The exhibit is historical and should not be used as current legal or wage guidance.

Methods and analytical boundaries

Tableau · Data preparation · Logistic regression · Decision trees · Model evaluation · Geospatial visualization · Statistical visualization · Analytical communication

These are distinct independent studies, not one combined dataset or client engagement. Original plots remain inspectable where underlying rows are unavailable. Quantitative comparisons are rebuilt only from values explicitly present in the source exhibits.