TL;DR: Yes. A 2024 study by Phạm Xuân Hậu of National Economics University, using Vietnamese firm data, finds fixed asset investment drops clearly when directors are aged 49 to 53, with a larger decline in small firms. This is evidence of how strongly belief shapes economic decisions, not evidence that tuoi han causes misfortune.
Why does this question matter for people aged 49 to 53?
If you run a business and are turning 49, 50, 51, 52 or 53, you may have heard someone say: this is a tuoi han year, be careful, do not expand investment. The real question is not whether you believe it, but whether that belief leaves a measurable trace in business behaviour.
Research by Phạm Xuân Hậu (2024), published in the Journal of Comparative Economics, shows Vietnamese firms cut fixed asset investment when their director is aged 49 to 53, and the decline is larger in small firms. This comes from a regression discontinuity design, comparing firms whose director has just crossed the age threshold with firms whose director has not, while other factors are controlled.
This study does not prove tuoi han is real. It proves that belief in tuoi han carries weight in economic decisions. Those are two very different things, and telling them apart is the first step in asking whether you are letting belief drive decisions unconsciously.
Research design: why is comparing just before and after the age threshold convincing?
The strength of regression discontinuity lies in comparing people who are almost identical in every respect except one age threshold. Someone born in December 1974 and someone born in January 1975 may be the same age for most of the year, but if the tuoi han threshold is counted by birth year, one has entered age 49 and the other has not.
Phạm Xuân Hậu (2024) uses exactly this approach: comparing firms whose directors sit just above and just below the tuoi han threshold, in the same period, same industry, same size, to rule out the influence of the economic cycle and firm characteristics.
If the result merely reflected that older people invest less for biological or life cycle reasons, the effect would appear gradually, not cluster exactly at the 49 to 53 threshold. The fact that the result clusters in the very age band folk tradition calls tuoi han suggests cultural belief, not biological age, is doing the work.
This design has limits. It cannot measure each director's motive. It cannot separate those who genuinely believe from those who do not but act under social pressure. And it does not say whether postponing investment leads to better or worse long term business outcomes. That is where evidence is missing, and it should be said plainly.
Tuoi han in folk tradition: are 49 and 53 the same as kim lau or tam tai?
In Vietnamese folk belief, ages 49 and 53 are often seen as two bad milestones in life, expressed in the saying "49 chua qua, 53 da toi". This is an oral saying, with no basis in any specific calendar calculation.
A clear distinction is needed: ages 49 and 53 in folk tradition are not kim lau, not tam tai, and not hoang oc. Kim lau is a calculation based on the lunar age of the person concerned, used to choose dates for marriage or house building. Tam tai is a three year cycle tied to the zodiac sign of each age. Hoang oc is six palaces counted by lunar age. These three methods have different calculations, different scopes, and none of them says that 49 or 53 is a fixed tuoi han for everyone.
Kim lau, tam tai and hoang oc are conventions of divination manuals, not calendar data that can be independently verified. They can only show that the system prescribes so, not that the prescription holds in reality.
If you want to understand more about how kim lau, hoang oc and tam tai are calculated and why the three are not one, you can read Checking ages for building a house in the 2027 Đinh Mùi year: which ages hit Kim Lâu, Hoang Ốc, Tam Tai, and why the three are not the same. That article goes into each method, while this one focuses on a different question: how the tuoi han belief affects investment decisions.
When does a belief bite hardest?
Kramer and Block (2008), published in the Journal of Consumer Research, showed that superstitious belief has two layers: a conscious layer, when people know they believe, and an unconscious layer, when belief affects decisions without people realising. The unconscious layer has a stronger effect on risky decisions.
This matters greatly for the tuoi han question. A director may say he does not believe in tuoi han, yet still delay a project because "things feel uncertain", still ask for more time to "think it over carefully", still scale down investment because "the economy is hard this year". Those reasons sound very reasonable, and may partly be genuinely reasonable. But if they appear exactly in the year the director turns 49 to 53, unconscious belief may well be contributing to the decision.
Kramer and Block show the unconscious layer operates independently of the conscious one. People do not need to believe in order to be affected. It is enough that the belief exists in the surrounding cultural environment, in family stories, in partners' reminders, in how the press talks about tuoi han.
How do businesspeople use feng shui to ease anxiety?
Tsang (2004), published in the Academy of Management Executive, argues that superstition both contradicts and complements business decisions. It contradicts because it rests on belief without empirical basis. It complements because it helps decision makers reduce anxiety in highly uncertain environments.
Tsang's argument is a theoretical claim, not yet replicated in many other empirical studies, so it should be read as a suggestive explanation, not a widely verified conclusion. Tsang also did not study Vietnamese businesspeople, but relied on conceptual analysis and general observation.
Nguyễn Hữu Thụ (2019), in research on Mother Goddess worship and the economy, recorded that those who seek out Mother Goddess worship in Vietnam are mostly businesspeople and traders. The author cites Ngô Đức Thịnh's observation that businesspeople make up the overwhelming majority of practitioners of this belief. This shows that in Vietnam, spiritual belief and economic activity are closely linked in practice, not two separate spheres.
Nguyễn Hữu Thụ's research focuses on Mother Goddess worship and does not directly measure the effect of tuoi han on investment. But it shows something important: in Vietnam, businesspeople do not treat spirituality and economics as two different matters. They turn to rituals to seek good fortune in business, and that belief can affect how they make decisions.
Table comparing the studies
| Study | Data scope | Method | Main result |
|---|---|---|---|
| Phạm Xuân Hậu (2024) | Vietnamese firms | Regression discontinuity | Fixed asset investment falls when directors are aged 49 to 53, more so in small firms |
| Kramer and Block (2008) | Consumers (United States) | Psychological experiment | Superstitious belief affects risky decisions, more strongly when the effect is unconscious |
| Tsang (2004) | Conceptual analysis | Management theory | Superstition both contradicts and complements business decisions |
| Nguyễn Hữu Thụ (2019) | Mother Goddess worshippers in Vietnam | Qualitative research | Most of those who seek out Mother Goddess worship are businesspeople and traders |
Note that these four studies have different data scopes. Kramer and Block studied American consumers, not Vietnamese businesspeople. Tsang analysed concepts, without field data. Nguyễn Hữu Thụ studied Mother Goddess worship, not tuoi han. Only Phạm Xuân Hậu (2024) directly studies Vietnamese firms on the question of tuoi han and investment. So one cannot infer from the other three how Vietnamese people are affected by tuoi han. One can only say that the psychological mechanisms described by Kramer and Block, or Tsang's argument, are plausible explanations for Phạm Xuân Hậu's result.
Why are small firms hit harder?
Phạm Xuân Hậu (2024) records a larger investment decline in small firms. This fits the logic: in small firms, investment decisions are usually made by one person or a small group, with fewer control processes, less constraint from a board or shareholders. In large firms, investment decisions usually pass through many layers, with an executive board and long term plans, so one person's personal belief can hardly affect the whole operation.
This also suggests that in small firms, the cost of postponing investment may be larger in the long run, since small firms usually have fewer reserve resources and less capacity to make up for missed opportunities. But this is logical inference, not a research finding. Phạm Xuân Hậu (2024) measures investment behaviour, not the long term business outcome of postponing investment.
What is the cost of postponing a decision because of tuoi han?
This section is Nhật Nguyệt's interpretation, not investment advice or a scientific conclusion.
When you consider postponing a project because this year is tuoi han, two things are worth asking yourself. First: without the tuoi han factor, would you still postpone? If the answer is yes, then tuoi han is not the real reason. If the answer is no, then you are letting a cultural belief affect an economic decision. Second: what is the cost of postponing? A missed opportunity, a partner turning to someone else, a market taken first by a competitor. Those costs can be measured, while the benefit of postponing usually cannot.
There is no right answer for everyone. Some find that postponing a year for peace of mind is a reasonable decision. Some find it an unnecessary cost. What matters is that you realise you are choosing, rather than letting unconscious belief choose for you.
Where is the evidence still missing?
Three things should be said plainly.
First, there is only one study that directly measures the effect of tuoi han on investment by Vietnamese firms. One study is not enough for a firm conclusion. The result needs to be replicated on other data, other periods, other industries.
Second, the study measures investment behaviour, not business outcomes. It is not clear whether cutting investment at ages 49 to 53 is right or wrong in the long run. It may help avoid risk, or it may cause a firm to miss opportunities.
Third, the study cannot distinguish between directors who genuinely believe and directors who do not believe but face social pressure. Both groups may cut investment, but their motives differ, and the appropriate response differs too.
There is not yet research measuring a director's personal level of belief in tuoi han against that same person's investment behaviour. Nor is there research comparing long term business performance between firms that postpone investment because of tuoi han and those that do not.
Conclusion: evidence about belief, not about tuoi han
The tuoi han belief leaves a measurable trace in investment by Vietnamese firms. That is Phạm Xuân Hậu's (2024) result. It is evidence of the power of belief in economic decisions, not evidence that tuoi han causes misfortune.
The effect is real, and it arises from belief: belief changes behaviour, behaviour changes outcomes. There is no need to call it tuoi han predicting correctly, nor to deny that the effect is happening. What matters is whether you realise you are letting that belief affect your decisions.
