The IPC does not involve any form of primary data collection, but rather uses available evidence in its analysis and undergoes a comprehensive assessment of all available evidence based on established criteria to assign reliability scores (R). Evidence on both outcome indicators (such as GAM based on WHZ, and GAM based on MUAC) as well as contributing factors (e.g. evidence diseases, feeding practices, and water and sanitation) should be evaluated, and an R should be assigned for each piece of evidence.
Evidence used in the IPC can have a reliability score of R2= reliable or R1= somewhat reliable. R1 is further divided into two scores: R1+ and R1-. R1+ refers to evidence that has good time relevance but is limited in terms of the soundness of the method or indicator used; R1- refers to evidence that has limited time-relevance but is considered good in terms of the method and indicator used. Outcome evidence that is limited both in terms of soundness of method and time relevance cannot be used in the IPC Acute Malnutrition classification. The assessment of reliability is not based on a statistically rigorous assessment, but rather on a general assessment of the soundness of methods of data collection and indicators used (M) and the time relevance of the evidence to current or projected analysis (T).
The Reliability Score Table for Acute Malnutrition Evidence (shown in Table 38) presents the general criteria for assessing reliability scores and provides more specific guidance on the assessment of the M and T for Acute Malnutrition evidence:
It should be noted that if the design effect of the GAM based on WHZ obtained at the higher administrative level is >1.7, these survey data should not be disaggregated for lower administrative levels.