What does the indicator describe?
The indicator of retail turnover measures the turnover in retail trade in Germany in the form of nominal and real (price-adjusted) index numbers and their change rates rather than absolute (monetary) turnover. Hence the indicator describes exclusively the development and not the level of turnover. The results presented both for retail trade as a whole and for its individual branches are based on the national Classification of Economic Activities, 2003 edition - WZ03. Since retail turnover is subject to strong seasonal variations, calendar- and seasonally adjusted index numbers are published, too.
How is the indicator calculated?
Retail trade statistics are sample statistics. About 27,000 of the total of approximately 378,000 retail businesses in Germany report their monthly turnover to the statistical offices of the Länder, while another 700 large enterprises submit their data directly to the Federal Statistical Office. At the Federal Statistical Office, the data transmitted by the Länder offices and the data of large enterprises are compiled to obtain a federal result. The (monthly) turnover established in this way is related to a base value (currently base 2003 = 100). The base value is the arithmetic mean of the twelve monthly turnover results for the base year. The index number regarding nominal turnover is calculated in the following manner: (monthly turnover/base value) x 100.
To obtain a real turnover index number, the turnover of the individual retail trade branches is deflated by using the relevant price indices and is then related to the price-adjusted base value. The data are adjusted for calendar and seasonal variations by means of the Census X-12-ARIMA method. The rate of change is determined by comparing an index number with the respective index number of the corresponding month of the preceding year.
The above calculations are made for all retail trade branches and their superordinate levels of classification (NACE 4, 3 and 2-digit levels) as well as for some special totals. Apart from the calculation of monthly index numbers, quarterly, half-year and annual index numbers are computed - and also index numbers for that period of the year which has just elapsed.
In the past, a new sample was drawn from the population of all retail businesses in Germany at about 10-year intervals. Plans have however been made to change that inverval to five year. In the interim, the basic sample will be updated by means of samples of new units.
When is the indicator released?
All retail turnover index numbers are released every month. About 30 days after the end of a reference month, first results are published in a press release (first release) in a rough breakdown by economic activities. Two weeks later, more comprehensive results are published on the internet in a more detailed breakdown by economic activities. At the same time, detailed results are available in the Genesis-Online database and the Publication Service. The release calendar and the press releases are available on the web site of the Federal Statistical Office.
How accurate is the indicator?
Like any sample statistics, the monthly retail trade statistics show a certain degree of uncertainty. However, larger inaccuracies observed in first releases in comparison to the results obtained later on have the following reasons:
- Not all businesses responsible for providing information keep the deadlines specified. The turnover of those businesses has to be added by the statistical offices in the form of estimates. Those estimates are later replaced by the original data.
- Though keeping the deadlines, some businesses report data which have been provisionally estimated by themselves. Those data are corrected later.
Consequently, the results require backward correction, but only for a maximum period of 24 reference months.