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of mature female whales. The relevant table from the Research Plan, which appears as Table 2 to
Appendix 6 (“Sample sizes of Antarctic minke, humpback and fin whales required for statistical
examination of yearly trend in biological parameters”) to that document, is reproduced below. The
far-left column shows that the JARPA II researchers considered using either a six-year or a 12-year
research period and the second column shows that they considered using either of two estimates of
the “initial rate” (i.e., whether the proportion of pregnant minke whales in the population of mature
female whales at the start of the research was 80 or 90 per cent). The researchers then calculated
how many whales would be required depending on the research period and the estimated “initial
rate” to detect different rates of change in the proportion of pregnant minke whales (shown in
percentages in the top row of the chart). The table is set forth below:
Research
period
6 years
12 years
Table 2. Total sample size of Antarctic minke whales required for statistical
examination of yearly trend [in the proportion of pregnant minke
whales in the population of mature female whales]
Initial
rate (%)
Rate of change
+1% -1% +1.5% -1.5% +2% -2% +2.5% -2.5% +3% -3%
80% 2022 2544 984 1089 618 591 462 369 402 249
90% 912 1617 609 663 - 348 - 210 - 138
80% 189 312 129 132 - 72 - 45 - 30
90% - 213 - 87 - 45 - 27 - 18
(Source: Counter-Memorial of Japan, Vol. IV, Ann. 150, App. 6.)
166. This table illustrates how the selection of a particular value for each variable affects the
sample size. For example, the decision to use a particular research period has a pronounced effect
on the sample size. In order to detect a rate of change of minus 1.5 per cent and assuming an initial
rate of 90 per cent (which were the criteria ultimately chosen by JARPA II researchers), a
six-year period requires an annual sample size of 663 whales while the 12-year period requires an
annual sample size of 87 whales. The table also illustrates that small differences in the rate of
change to detect can have a considerable effect on sample size. For example, in order to detect a
change of minus 1 per cent over a six-year period (assuming an initial rate of 90 per cent), the
required yearly sample size is 1,617 whales. To detect a change of minus 2 per cent under the
same circumstances, the required yearly sample size is 348 whales.
167. The fourth step is the selection of a particular sample size for each research item from
the range of sample sizes that have been calculated depending on these different underlying
decisions relating to level of accuracy, rate of change and research period. With respect to the