1. Defining The Sample Survey of Pesticide Using in Agriculture
Olga Grakoviča
Mathematical Support Division

2. The target population and sample size
The target population is farms, which are growing wheat. The number of farms in the sampling frame is
The sample size is 1 000 farms.

3. The biggest wheat growing farms
The data is sorted by district and wheat growing area in descending order. Cumulative sum of wheat growing area in each district computed (the cumulative sum of wheat growing area for the 1st farm will be the wheat growing area of the 1st farm, the cumulative sum of wheat growing area for the 2nd farm will be the sum of wheat growing area of the 1st and 2nd farm, so on...);
The biggest farm are classified as "big" one by one, while the cumulative sum of wheat growing area is equal or exceeds 56% of the total wheat growing area in district.

4. Sample design for smaller farms
Stratified sampling design, where stratification variables are:
territory (by district);
wheat growing land area.
155 strata
370 farms have selected as a stratified sample, other farms in sample are big and included without sampling.

5. Grouping by wheat growing area in district bounds
A1=max( wheat growing area ) – the first point of interval;
A2=A1/2.5 – the second point of interval; …
An=An-1/2.5 – if An>1. The last fixed point of intervals is minimum of An. So the last interval is [0,An]. The biggest number of groups is 8.

6. Allocation
The sample size is determinate based on Neyman optimal allocation in each stratum:
where
is wheat growing area.