A data dashboard is a visual summary of information that helps people monitor patterns, compare groups, and make decisions quickly. Dashboards often combine key performance indicators, charts, tables, filters, and alerts on one screen. Reading them well matters because a polished display can still hide bias, missing context, or misleading design choices.
Good dashboard reading means asking what is being measured, how it is filtered, and whether the visual evidence supports the conclusion.
Key Facts
- A KPI is a key metric chosen to summarize performance, such as total sales, average score, or percent completed.
- Mean = sum of values / number of values.
- Percent change = (new value - old value) / old value x 100%.
- Rate = count / total, such as conversion rate = conversions / visitors.
- Always check filters, time range, units, and sample size before interpreting a chart.
- Avoid comparing chart areas or 3D shapes when length or position on a common scale would show the data more accurately.
Vocabulary
- Dashboard
- A dashboard is a visual display that combines multiple data views to summarize a situation or track performance.
- KPI
- A key performance indicator is a selected metric used to judge progress toward a goal.
- Filter
- A filter limits the data shown by category, date, location, or another condition.
- Trend
- A trend is a general pattern of increase, decrease, or stability over time.
- Axis Scale
- An axis scale is the set of values used on a chart axis, which affects how large or small differences appear.
Common Mistakes to Avoid
- Ignoring the active filters, which is wrong because the dashboard may be showing only one region, date range, product, or subgroup instead of the full data set.
- Treating a large KPI number as automatically good, which is wrong because the number needs a unit, goal, baseline, and comparison period to have meaning.
- Comparing charts with different scales, which is wrong because the same visual height or slope can represent very different amounts depending on the axis.
- Assuming correlation proves causation, which is wrong because two dashboard metrics can move together due to a third variable or coincidence.
Practice Questions
- 1 A dashboard shows 1,250 website visitors and 75 purchases for one day. What is the conversion rate as a percent?
- 2 A KPI card shows revenue increased from 60,000 this month. Calculate the percent change.
- 3 A dashboard shows a line chart with a steep upward trend, but the y-axis starts at 90 instead of 0 and the data covers only three days. Explain why this design might be misleading and what you would check before making a decision.