Regular Examination of the Statistical Accuracy of the Tankan
February 22, 2019
Research and Statistics Department
Bank of JapanThe Bank of Japan examines the statistical accuracy of the Tankan (Short-Term
Economic Survey of Enterprises in Japan) regularly (once a year in principle), toprevent the lowering of statistical accuracy due to a decrease in the number of sample
enterprises resulting from bankruptcies, mergers, and other factors. When the accuracy
is not sufficient, the Bank adds new sample enterprises. The recent examination showedthat the statistical accuracy after the December 2018 survey satisfied the criteria. The
total number of the sample enterprises for the March 2019 survey will be 10,040(including 210 financial institutions).
Note: For details of the statistical accuracy of the Tankan, please refer to "Explanationof the Tankan (Short-Term Economic Survey of Enterprises in Japan)," February
2019.
Details of the examination are as follows.
1. Sample Distribution
In the Tankan, the population is determined as private enterprises with capital of 20
million yen or more (excluding financial institutions). The population is classified into
389 strata by industry, enterprise size and sales for the estimation of the population
total.1 The Bank examined whether there is a statistically significant difference in thesestrata between the sample and population distributions.2 The result showed that there
was no stratum in which the sample distribution was deemed to deviate from thepopulation distribution.3
1

In the Tankan, the Bank places the restriction on selecting sample enterprises in order to limit
disturbance to the estimates due to an idiosyncratic factor of a sample enterprise: the sampling ratioof each stratum is maintained at 0.5 percent or more. The Bank verified that there was no stratumwith sampling ratio of less than 0.5%, along with the examination of the statistical accuracy on theabove.
2
The "test of the goodness of fit" using chi-square distribution is used in the regular examination.
This method tests the null hypothesis, H0: "There is no significant difference between the sample
and population distributions." When the hypothesis is statistically rejected, the sample distributions
are deemed to deviate from the population distributions.
3
In the Survey of Financial Institutions, the population is determined as financial institutions with
10 employees or more. The population is classified into 23 strata by sector and the number ofemployees. The Bank examined whether there is a statistically significant difference in these strata

12. Standard Error Ratios
The Bank examined the standard error ratio of sales 4 in manufacturing andnonmanufacturing for each enterprise size in the Tankan. The results showed that thestandard error ratios remained within the criteria — 3% or less for manufacturing and
5% or less for nonmanufacturing — as listed in the table below.5Standard Error Ratios of SalesManufacturing

ActualLargeEnterprises

Medium-Sized
Enterprises

SmallEnterprises

0.7%

1.8%

1.8%

Criterion
Nonmanufacturing

Actual

3.0% or less
1.2%

Criterion

2.2%

1.7%

5.0% or lessInquiries
Business Survey Group, Economic Statistics Division, Research and Statistics
Department
E-mail: post.rsd5@boj.or.jp

between the sample and population distributions. The result showed that there was no stratum inwhich the sample distribution was deemed to deviate from the population distribution.
4Standard error ratio shows how accurate an estimate of the survey population mean is. It iscalculated by dividing the standard deviation of the sample mean by the survey population mean.
5In the Survey of Financial Institutions, the Bank examines the standard error ratio of fixed andsoftware investment (excluding land purchasing expenses) for overall financial institutions. The
result showed that the standard error ratio was 6.2%, remaining within the criterion, 10%.

2