EFGS Vienna, 11 November 2015, Mr. Niek van Leeuwen, Non disclosure rules applied on non-hierarchical small areas

Regular non disclosure rules Minimum number. N>= 3. Dominance rule on total sum: Size is identifying. ( Total sum – Max -1 – Max ) X% Average: Equality is identifying. abs(Max – Max (estimate) ) > p * Max / 100, p > X% Max (estimate) = Total sum – (N -1 ) * Max -1 2

Regular non disclosure rules 3 Secondary non-disclosure. Combination with larger, hierarchical areas

Different small areas 4 Disclosure when combined with publically available sources. NL: The base register on addresses (PC) and buildings (coordinates, grid). But there is a larger demand for small area statistics for different types of areas. -Grids -Postal codes

Types of intersection 5 Differencing whole coverage Differencing partly covered Z-type R-type

Types of intersection 6

Results so far 7 Iterative approach, initially: -Frequencies: Rounding on 5. -Percentages; Rounding on 10%, minimum 10 persons/dwelling. -No non disclosure of groups applied.

Results so far 8 Grid 100 meter Postal code Data after non disclosure Combination Z-type

Optimising, different scenario’s 9

Optimising 10 Promising scenario’s so far -Suppress small numbers less than 5. -Rounding frequencies to 5. -Percentages rounding to 10%, minimum = 10 persons. -Small numbers? 10 persons total and 10% score is 1 person! -Diminishing number of categories. Introducing 5 to 7 categories.

Future Generic rules disclosure controle for combinations of non hierarchical areas Report 2016, Q2/Q3. 11

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