A midlife career change is what many of us dream about, but few dare to take the step. It is a big gamble to leave behind a well-established career, stable income and settled work relationships in favour of the unknown. But Hong Kong University academic Paul Yip Siu-fai is doing just that. One of the city's leading statisticians, he has decided to become a social worker. With the blessing of the university, the senior lecturer switched to the department of social work and social administration in July. Now instead of crunching numbers and dealing with statistical methodology, he takes on society's problems. But to do his job, Dr Yip, 47, has had to reinvent himself and test his personal limits. He's also had to learn the jargon of his new job. On the phone, Dr Yip speaks about grass roots, single mothers and poverty, and sounds more like a social work professor than a number cruncher. In person, however, the habits of his former calling betray him. While he talks, he repeatedly draws charts and graphs on a white board to illustrate his points. His desk is full of formula-filled proposals and number-based write-ups for overseas journals. Dressed in a blue shirt and tailored grey trousers, he resembles an office manager. He appears stern, cautious, suspicious, and smiles only when prompted. 'I'll give you 15 minutes more and let's finish our interview at six,' he says suddenly in the middle of our conversation before I've even had the chance to ask about his personal life. He may appear conservative, but such impressions are deceiving and are in stark contrast to his vocal and impassioned attitude to many social problems. In the mid-1990s, before many people noticed the problem, Dr Yip was raising the alarm about Hong Kong's ageing population. In 2000, when the government denied right of abode to mainland-born adult children of Hong Kong parents, he bravely took a stand, arguing they should be allowed in to bolster the number of young people in the city. Two years later, he started an unprecedented series of studies on suicide in Hong Kong, arguing the problem was getting worse as the economy went downhill. And recently he stepped into the area of poverty, engaging in a public debate - via a series of newspaper columns - with University of Science and Technology economist Francis Lui Ting-ming, who insisted there was no rich-poor gap. Dr Yip wants to do more and he hopes that by changing fields, he can focus on researching social issues. He wants to use his expertise in statistics to put society's problems down in hard figures. 'Behind the numbers, there are a lot of stories and they reflect a situation. It can increase understanding of the whole problem,' he says. 'I keep developing new techniques to understand people's livelihoods. Data will also give me evidence to prove problems exist.' Though using statistics to demonstrate the extent of social problems is not new, Dr Yip's skills give him a special role in the field. Journalists often call on him to provide numerical proof of trends, and he is often on television talking about suicides - a particular passion - and population issues. Born in Lin Tong Mei village in Sheung Shui, Dr Yip was the youngest of six children. His passion for statistics grew out of an early interest in maths. 'My maths teacher used real-life examples to teach maths to stir our interest,' he says. He studied statistics at the University of Melbourne. In 1991, he joined Hong Kong University as a lecturer in the department of statistics and actuarial science. 'In the past, I was only concerned with developing new methods of statistics,' he says. But his passion for social issues began with a phone call in 1993. 'A reporter called me and asked whether there were patterns of students' suicides. I told her that I needed to gather the figures and would get back to her in two days.' The research, which he did in his own time, received added impetus after the suicide of a close friend. 'I felt bad and I still feel bad,' he says. 'It gave me the conviction to save more lives. I can see the pain it inflicted on the survivors.' He helped to persuade the Jockey Club to donate HK$22.3 million to set up the university's Centre for Suicide Research and Prevention. He also built the core team that tackles the issue today. Soon, the research was producing important information: charcoal burning was a new mode of suicide which took 213 lives out of 1,000 in 2005; front-page reports of suicides caused copycat incidents; and most of those committing suicide were not mentally ill. 'Many who killed themselves were male, middle-aged and had jobs,' Dr Yip says, adding that many had relationship problems. Apart from inventing a way of calculating the economic cost of suicides, he also developed a statistical methodology to predict the number of suicides in a year, which in turn allowed social workers to evaluate in advance the impact of preventive measures. And in a more direct way, he helped prevent suicides by persuading supermarkets to print hotline numbers and suicide prevention information on charcoal packaging. He also convinced the Housing Department to change the design of kitchen windows in public estates as suicide victims commonly jumped to their deaths from there. His team also started a community network to prevent suicides in Tuen Mun and Eastern District, as well as counselling for bereaved families. Dr Yip's expertise and energy have helped the city discover the true extent of many social issues. When experts attributed low fertility among married women to their preference for not having children, he proved his suspicion that employment was the cause. 'I found out that while the fertility rate is dropping, the labour participation rate of women is rising,' Dr Yip says. 'Work has been competing against having children.' He says targeting people who already have two children to have three would do little to remedy the problem. Instead, the focus should be on those who have one or no children as they are in the majority. His decision to work full time in the area of social work wasn't easy, and it took him a year and a half to make the decision. Giving up a long-established career is one concern; uncertainties are another hurdle. 'I am a statistics person. I am afraid people in the new department won't accept me,' he says. His wife Karen, a university administrative officer, was also concerned. When the vice-chancellor gave the green light, the father of three decided to give it a try. With the help of department head Sandra Tsang Kit-man, the transition has been smooth. 'I am grateful for Sandra's support. She gave me time to settle in and assigned me to teach research as a start,' he says, adding that he is comfortable with this assignment. Dr Tsang says she doesn't mind Dr Yip not having had social work training, because he can approach social problems from an alternative perspective. What is valuable is not just his expertise in research, she says, but also his ability to teach new courses such as social needs for population changes and suicide research. Dr Yip, who will start teaching in January, says he does feel pressure. 'I wasn't trained in social work,' he says. 'People may ask what kind of contribution I can make to the department.' But the devoted Christian, who has developed coping skills after studying so many wasted lives, has his own way of dealing with stress. 'Pressure is an opportunity to develop myself,' he says. 'There are always uncertainties. Somehow we have to find the courage to meet the challenge.' Academics, including Chinese University social work professor and poverty expert Wong Hung, have been watching Dr Yip's move with interest. 'He has become a social worker,' he says when Yip Siu-fai's name is mentioned. Professor Wong says it is the first time he has seen an academic changing departments after being well-established in a field. 'Such a switch is rare and involves a risk,' he says. 'He has to adjust to new colleagues and has to write for social work journals.' But he admires Dr Yip's move. 'He now talks about the M-shaped economy and the wealth gap,' Professor Wong says. 'Statistics is only a technique. But he uses his technique and figures to find out the reasons behind a phenomenon and to help vulnerable groups voice their problems. It is a contribution to society.' He adds that such figures-based policy advocacy can pressure the government to act because public officials tend to trust statistics. Social worker Ng Wai-tung agrees, saying having a statistician join the field would equip workers with better research skills for proving problems. Dr Yip, 47, says he is changed by the work he has done. 'Many people who committed suicide were unfortunate, suffering abuse as a child, which is beyond their control. I am very fortunate I can use numbers to help people.'