In April 2011, the index of production in the construction sector in Bulgaria, calculated on the base of seasonally adjusted data, was 2.7% below the level recorded the previous month.

The preliminary data was released Tuesday by the National Statistics Institute, NSI.

In April 2011, work day adjusted data showed a drop of 22.8% in construction production, compared to the same month of 2010.

In April 2011, the construction production was below the level of the previous month.

Indexes of the production of building construction, calculated from the seasonally adjusted data fell by 1.8%, while the production of civil engineering - by 2.4%.

On annual basis, in April 2011, the decrease of production in construction, calculated from work day adjusted data, shows a drop of 29.3% in civil engineering, while building construction decreased by 17.2 %.

Seasonal adjustment is a statistical method, which eliminates the seasonal component of time series and it is particularly suitable for longterm comparisons and analysis of the data.

Work day adjustment is an adjustment for variations in monthly data, caused by calendar effects, different number of calendar and work days in the month, and national holydays - for example the presence of more days off in May could contribute to the decline in the production in some activities.