On the basis of her work inlinear programming, she started work at the London School of Economics in the late 1950s. In 1960, Doig and fellow LSE mathematician Ailsa Land, published a landmark paper in the economics journal Econometrica, which outlined a branch and bound optimisation algorithm for solving NP-hard problems. The algorithm has applications in many fields, including transport logistics and beam angle optimisation in radiation therapy treatment.
University of Melbourne
In 1963, Doig returned to Melbourne, where she took up a position as a senior lecturer in statistics at the University of Melbourne. In the mid-1960s, she joined a team headed by the sociologist Ronald Henderson which was attempting to quantify the extent of poverty in Australia. The team developed the Henderson Poverty Line in 1973, which was the disposable income required to support the basic needs of a family of two adults and two dependent children. The techniques developed by the Henderson team have been used by the Melbourne Institute of Applied Economic and Social Research to regularly update the poverty line for Australia since 1979. In 1970, Harcourt took study leave in Sweden, where she co-authored two papers on theoretical chemistry—"A simple demonstration of Hund’s Rule for the helium 2S and 2P States" and "Wavefunctions for 4-electron 3-centre bonding",—with her husband, the chemist Richard Harcourt. In 1975, following the dismissal of the Whitlam government, Harcourt and fellow statistician Malcolm Clark noticed irregularities in the distribution of party ordering on the Senate ballot papers for the 1975 federal election which was determined by drawing envelopes from a box, with Coalition parties holding one of the first two positions in every state. Harcourt and Clark made a submission to the Joint Select Committee on Electoral Reform, which resulted in a 1984 amendment to the Commonwealth Electoral Act to introduce a more rigorous double randomisation method. Harcourt and Clark published a paper about their analysis and recommendations for the Australian & New Zealand Journal of Statistics in 1991. Harcourt retired as an academic from the University of Melbourne in 1994, but continues to work there as a sessional tutor in statistics. In October 2018 Harcourt was named as 2019 Senior Victorian Australian of the Year. In early December 2018, the University of Melbourne awarded Harcourt with an honorary Doctor of Science degree. In June 2019, Harcourt was made an Officer of the Order of Australia in recognition of her "distinguished service to mathematics and computer science through pioneering research and development of integer linear programming".