⁽¹⁾ The term participation rate’, used in this note, means the same as the term ‘activity rate’, used in the description of the official projections.

⁽²⁾ Economic Trends, no. 107, September 1962. For each age group between 30 and 65, however, there has been a marked and continuous rise in the activity rate … there must in any case be an upper limit to the activity rates for married women. The problem … is to estimate where this limit lies … Attempts to fit curves to the past data … have provided little guidance … and the projections are therefore based on a continuation of the rate of growth of the last few years … ‘The past data to which reference is made here are clearly data on the simple activity rates over time for given age groups.

⁽³⁾ Strictly speaking the cohort participation-rate profiles presented here are not entirely for the same women, since as the women become married they move from a single women's cohort into a married women's cohort. But as the movement back (through widowhood or divorce) is negligible, this does not significantly affect the interpretation of the cohort profiles used here, after the age (about 30) when most of the women who are ever going to be married have got married.

⁽⁴⁾ The data used here are not the participation rates during the period 1952 to 1961, but the trend values of these rates, extended to 1962. This was done so as to abstract from quite sharp year-to-year fluctuations in participation rates which resulted chiefly from changes in the pressure of demand for labour. Straight-line trends were fitted to the logarithms of the participation rates. We might in some age-groups have used curvilinear trends flattening off in the last four years, but did not do so, as we took this flattening to be the conse quence of a weaker demand for labour. This method resulted in 1962 trend values of participation rates that were generally well above 1962 estimates of actual values. For all age groups combined these 1962 trend values gave a female labour force (both single and married) which was 150 thousand bigger than the estimated actual mid-1962 labour force.

⁽¹⁾ There are two exceptions (table 1) : the changes in the participation rates between the ages of 20-24 and 25-29, and those between the ages of 55-59 and 60-64. Where we have used the average of these changes, our results probably do not give much better guidance than the alternative approach.

⁽¹⁾ These educational assumptions are highly provisional. In calculating the effects of the assumptions on working population, we have extrapolated the past trends in the relationships between those at school in the final compulsory year and those staying on in subsequent years. We have also completely excluded those staying on in full-time education from the labour force. The marriage-rate assumptions are taken from D. C. Paige, Birth and Maternity Beds in England and Wales in 1970’, National Institute Economic Review, no. 22, November 1962. These and other assumptions will be described at length in the full study of the longer-term prospects for the British economy which is due to be published next year.

⁽²⁾ There is no theoretically completely satisfactory method of allocating the separate contributions made to the change in the female labour force by changes in participation rates, marital status, total female population and age-structure. A method that gives reasonable approximations, however, has been used and is explained in the note below. Corresponding calculations for the past ten years and for the total labour force (males plus females) will be shown in the larger study mentioned above. The results shown above have been obtained by applying the method to our ‘trend’ values of the data in 1962 and 1972 for our projection, and to the official ‘trend’ values for 1962 for the official projection (see footnote 4, page 56).