Evidence reconstruction
Most decisions rest on numbers that nobody has traced to a source. DDA traces each number, records what it measures, and states what it cannot show. The result is an evidence base that a hostile reader can check.
01 What the work does
A public claim, a forecast, or a plan usually cites figures from several places. The figures can come from different years, use different definitions, and describe different geographies. A census table for a city can describe the whole metropolitan area. A vacancy rate can come from a survey that does not cover the town in question. A report can repeat a figure that traces back to one older source.
DDA finds the primary source for each figure. We record the table, the release date, the geography, the definition, and the data lag. When two sources disagree, both stay in the record until the analysis resolves the difference. When no public source exists, the record says so.
02 The register
Every figure goes into a register before it enters an analysis. Each row has a status.
ACTUAL means a direct extract from a named primary source. The row gives the table number, the release date, and the data lag.
PROXY means the figure comes from two or more primary items. The row shows every step of the derivation, and the register states how the proxy differs from the quantity that the analysis needs.
FLAG means we tried to extract the figure and found no usable public source. The row names the gap, states the assumption that fills it, and states what the gap does to the result.
Figures that a client supplies carry a separate label, SOURCE-STATED. They are useful and they never carry a conclusion alone.
Each row also holds the value, the unit, the geography, the reference period, the source, the publication date, and any conflicting figure. A reader can start from any number in a report and reach its row in one step.
03 Rules the register enforces
No number enters an analysis unless it exists in the register. Each quantity has one value in each document. A derived figure shows its steps. A conflict between sources stops the analysis until we resolve it or disclose it.
The register also records absences. A mandate with no budget line, a warning with no documented response, and a decision with no recorded reason are findings. DDA records the absence, names the organization that holds the missing record, and states what depends on it.
A published record does not always show that something did not occur. DDA separates two statements: the record does not show X, and X did not happen.
04 What the work can produce
The evidence base can take several forms. A primary-source register lists every figure with its status. A chronology places decisions, statements, and events in date order. A contradiction log lists each place where sources disagree. A corrections log shows each figure we changed, the original value, and the reason. A pull list names the public sources that we still need to extract and the order that resolves the diagnosis fastest.
A verification appendix gives an access path for every claim: the URL, the query, or the document page. Any reader can recheck any claim without asking DDA.
05 Where it applies
Every other DDA capability starts here. A fiscal model needs a register of its inputs. A workforce analysis needs the source of each count. An institutional analysis needs the primary source for each public claim. Evidence reconstruction also works as a stand-alone assignment. A team can hand DDA a report, a strategy, or a set of conflicting numbers and ask for the record behind them.
See also Institutional and policy analysis for claims that cross mandates and budgets, and When an unsupported number carries the answer for the cost of an unresolved input.
06 Bring the material
Send the report, the number, the public claim, or the pile of records. DDA will identify the first figure that the conclusion depends on and check it against its source.