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Appendix C
Price Index for the Cook Islands 1891–1959

In equating the buying power of money at different periods of time absolute precision can never be attained, but even a reasonable degree of equivalence can enable comparison over time, and at least indicate the direction of trends in buying power. In the case of the Cook Islands, during the whole period from 1891 to 1959 the great bulk of its trade has been with the mainland of New Zealand. As almost all consumption goods which are purchased for cash were imported from the mainland, the relative buying power of the pound in the Cook Islands has been closely geared to New Zealand prices. Admittedly the relative proportions of various consumption items differ somewhat between the mainland and the islands but in general there appears to have been a close correlation in relative purchasing power between the two places.

In order to obtain some indication of trends in per capita buying power derived from exports of agricultural produce (which has always been the major source of cash income in the group) the following price index was constructed. The base year for the whole index is 1955 (which is taken to equal 1000). For the years 1907 to 1959 the New Zealand Retail Price Index was used,¹ and for the years 1891 to 1906 the New Zealand Index of Retail Prices for Groceries was taken.² The scale of the latter index was calibrated to equivalence with that of the former on the basis of the relationship between the averages for the five-year period 1909–13 from both indices.

1891	312	1911	306	1931	479	1951	828
1892	298	1912	315	1932	443	1952	892
1893	314	1913	322	1933	420	1953	933
1894	301	1914	332	1934	427	1954	976
1895	287	1915	357	1935	442	1955	1000
1896	295	1916	382	1936	456	1956	1035
1897	305	1917	415	1937	488	1957	1057
1898	314	1918	449	1938	502	1958	1104
1899	285	1919	482	1939	523	1959	1146
1900	295	1920	538	1940	547
1901	302	1921	546	1941	567
1902	316	1922	503	1942	586
1903	306	1923	507	1943	599
1904	299	1924	520	1944	610
1905	330	1925	530	1945	618
1906	333	1926	533	1946	623
1907	308	1927	529	1947	643
1908	309	1928	531	1948	694
1909	305	1929	530	1949	706
1910	308	1930	518	1950	745