Back to the lesson·Lesson 6 of 8·Counting people
Somebody has already defined this
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What this lesson covers
- The question to ask before writing a definition
- Where the definitions live
- Adopt, adapt, or invent
- Documenting a departure
- Map to the standard where you can
- Comparability is the whole point
- SDG tiers, and what they tell you
- When the standard is wrong for you
- What comes next
Speaker notes
Where the published definitions live, a rule for choosing between adopting one and writing your own, and how to document a departure so your number stays comparable.The question to ask before writing a definition
- Almost every indicator this sector reports has already been defined by somebody with more time, more consultation and more scrutiny than you will get.
Speaker notes
Almost every indicator this sector reports has already been defined by somebody with more time, more consultation and more scrutiny than you will get. Finding that definition takes twenty minutes and it changes what you write. The reason is not deference. It is that a number nobody can compare to anything answers half the question. A GAM prevalence that cannot be read against the IPC phase thresholds, or a coverage figure computed differently from the ministry's, has thrown away most of its value in exchange for local convenience.Where the definitions live
Source Covers Note WHO Growth standards, immunisation, disease surveillance case definitions The growth standards are the authority for anthropometry, full stop UNICEF Child protection, WASH, education, nutrition indicator definitions Usually the most operationally detailed Sphere Minimum standards and their indicators across humanitarian sectors Gives thresholds, not just definitions The SDG framework 231 global indicators with metadata sheets The metadata sheet is a reference sheet; read it as a model IPC Acute food insecurity and acute malnutrition classification Defines the evidence, not just the indicator SMART Nutrition survey methodology and plausibility criteria Defines how the data is collected, which is half the definition JMP Water, sanitation and hygiene service ladders The ladders are indicator definitions in disguise The cluster Whatever the response is reporting on this year Least stable, most immediately binding Speaker notes
Two of those deserve emphasis for this audience. The JMP service ladders are definitions, not categories — "basic" water service is an improved source within a 30-minute round trip, and a programme classifying on source alone is not reporting the JMP indicator whatever it calls it. And the SDG metadata sheets are the best free model of a reference sheet you will find; read two of them before writing your own.Adopt, adapt, or invent
- Adopt — when a standard definition exists and you can compute it
- Adapt — when the standard definition exists but you genuinely cannot compute it, usually because a data element is…
- Invent — only when the thing you need to measure is specific to your programme and nobody else measures it
Speaker notes
A rule that resolves most cases: Adopt when a standard definition exists and you can compute it. This is the default and it should cover most of your LogFrame. Adopting means adopting the whole thing — numerator, denominator, age bands, recall period — not the name. Adapt when the standard definition exists but you genuinely cannot compute it, usually because a data element is missing. Adaptation is legitimate and it must be documented, because an adapted indicator carrying the standard name is the worst of both worlds. Invent only when the thing you need to measure is specific to your programme and nobody else measures it. Rarer than people think. Before inventing, check whether the thing you want is really a disaggregation of a standard indicator, which it usually is.Documenting a departure — Example
Standard WHO/UNICEF, penta3 coverage (WUENIC methodology) Departure Denominator uses MoH facility catchment estimates rather than UN WPP surviving infants. Numerator restricted to facilities reporting in the month, where the standard uses all facilities with non-reporters imputed from the previous year. Effect Our figure is a lower bound relative to the standard. On 2024 data the difference is largest in August, where reporting completeness was 29%. Comparable to Other districts using the same MoH denominators. Not directly comparable to WUENIC national estimates.Speaker notes
The reference sheet gets two more fields when you depart from a standard. Four lines, and the last one is the one a reader needs most. Say what your number can be compared to. Most misuse of an indicator is comparison against something incomparable, and it is almost always done in good faith by somebody who had no way to know.Map to the standard where you can — In Python
DEFINITIONS = { "local_gam_muac": lambda d: (d["muac_mm"] < 125) | (d["oedema"] == True), "who_gam_muac_only": lambda d: d["muac_mm"] < 125, } for name, rule in DEFINITIONS.items(): eligible = d = muac[muac["muac_mm"].notna()] print(f"{name:22} {rule(d).sum() / len(eligible):.2%} (n={len(eligible)})")Speaker notes
Where you have person-level data, you can often compute both your definition and the standard one and publish the pair.Map to the standard where you can — In R
muac |> filter(!is.na(muac_mm)) |> summarise( local_gam_muac = mean(muac_mm < 125 | oedema), who_gam_muac_only = mean(muac_mm < 125), n = n() )Speaker notes
Publishing both costs two lines of code and settles a question that would otherwise take an email thread. It also makes the effect of your departure a measured quantity rather than an assertion — which is the same move the cleaning log makes for every cleaning rule.Comparability is the whole point
- Against yourself, over time. A definition changed between rounds breaks the series, and the break is invisible…
- Against your neighbours. Cluster reporting aggregates partner figures. A partner using a different denominator…
- Against the threshold that triggers action. IPC phases, Sphere minimum standards and the 15% GAM emergency…
Speaker notes
Three places where a locally-invented definition costs you concretely: That last one is not hypothetical. MUAC-based and weight-for-height-based GAM give different prevalences on the same children, and the IPC acute malnutrition thresholds are defined for specific measures. Name the measure in the indicator name —gam_muac_percentandgam_whz_percentare different indicators that both get called "GAM".SDG tiers, and what they tell you
- Tier 1 — definition agreed, data regularly produced by most countries.
- Tier 2 — definition agreed, data not regularly produced.
- Tier 3 — no agreed definition yet. (Formally retired as a tier, but the situation it described is everywhere.)
Speaker notes
The SDG framework classifies its indicators into tiers, and the classification is useful well beyond the SDGs. If your indicator is tier 3 in substance — no agreed definition — you are inventing, and you should expect to spend time defending it in every review. That is sometimes the right call. It is never the cheap one, and knowing which tier you are in tells you how much documentation the indicator will need for the rest of its life.When the standard is wrong for you
- The age band does not match your programme. A standard defined for under-fives in a programme serving 6 to 23…
- The recall period does not fit the context. A seven-day food consumption recall in a context with a fortnightly…
- The denominator is unavailable, and the standard assumes a census that does not exist for your area.
Speaker notes
Occasionally it genuinely is, and adopting it uncritically is its own failure. In each case, adapt and document. What you must not do is keep the standard's name, change its guts, and let a reader assume comparability that is not there.When the standard is wrong for you
Adopting a standard definition is not a loss of analytical independence. It is what makes your number legible to everyone who has to act on it.
What comes next
- You have a definition, a denominator and a standard to compare it against.
Speaker notes
You have a definition, a denominator and a standard to compare it against. The last unit is about the two numbers placed beside it — the baseline it started from and the target it is supposed to reach — and what each of them does to the behaviour of the people being measured.