2020年第一季度中国爆发了新型冠状肺炎疫情，由于湖北和武汉被封锁，多个省市实施隔离措施，导致中国大部分经济活动暂时中止。第一季度，中国的实际GDP同比缩水6.8%。很多人关注2020年中国的实际GDP水平，它主要取决于两方面发展，一是疫情过后经济的复苏速度，二是经济刺激措施是否到位。

在表1中，我们按照6.9这一2019年人民币兑美元的平均价格，分别用人民币（第2栏）和美元（第3栏）列出了中国从2015年第一季度以来各季度的GDP水平。此外，在第4栏和第5栏列出了GDP的季度同比和环比实际增长率。我们首先注意到，中国的GDP季度同比实际增长率是逐年下降的。而且，在2019年，由于当时中美贸易战不断升温，中国经济增长明显放缓，目前仍受其负面影响。从表1可以看出，中国GDP的季度同比增长率已从2019年第一季度的6.4%逐步下降到2019年第四季度的6.0%。如果中国没有暴发新冠疫情的话，其2020年第一季度GDP有可能比2019年第一季度的21.81万亿元增加大约6.0%，达到23.12（21.81×1.06）万亿元。这是我们对2020年第一季度GDP的假设估计，实际上，2020年第一季的GDP是20.32万亿元。所以，估计新冠疫情给中国带来的GDP损失是假设GDP与实际GDP之差，即2.8万亿元人民币（4050亿美元），或者说是2019年中国99.09万亿元GDP总值的2.8%。

不过，今年第一季度中国GDP较去年第四季度出现下滑也并不是反常的。对表1第5栏的观察表明，这种情况经常会发生。从2015年到2019年，第一季度的非年化GDP均出现环比下降，降幅平均达16.9%。当然，这一降幅与2020第一季度实际下降26.9%不可同日而语。另外，第一季度GDP占全年GDP的比重往往不到22%，而第四季度GDP在全年GDP中的比重通常超过28%。这是由于中国通常在1、2月份有春节（农历新年）假，在这期间，所有农业、制造业、采矿和建筑活动都会停止。

图1同样是显示按2019年价格计算的中国2015年第一季度以来的GDP水平。对于2020年第一季度，我们在同一个柱子上标出了GDP实际水平（纯色）和假设增长水平（条纹），假设增长部分就是我们所估计的新冠疫情给全国GDP造成的损失，即2.8万亿元。图1清楚地证实了我们通过表1所观察到的季度GDP的明显季节性，特别是第二季度的环比增长速度（绿柱到红柱）要远远高于第二季度的同比增长速度（红柱到红柱）。事实上，在过去五年里，第二季度GDP的环比平均增长率达到11.4%（见表1第五栏）。

因此，在正常情况下，2020年第二季度的GDP预计将比第一季度增长11.4%，，达到22.64万亿元（20.32×1.114）。预计第三季度GDP将比第二季度增长4.3%，达到23.61万亿元，第四季度增长10.3%，达到26.04万亿元。就2020年全年来说，把2020年第一季度的实际GDP与第二、第三、第四季度的预测GDP加起来，全年GDP预计为92.61万亿元。比2019年的99.09万亿元低了6.5%，这个数字似乎是太低了。而且，这些预测都是基于这样的假设，即中国没有出现复苏效应，也没有出台额外的经济刺激措施。

上述分析的一个主要缺点是，没有考虑到2020年第二季度的增长只是达到先前已有的产出水平，而不是新一轮增长，所以，它的增长速度实际上应该更快。想想看，一个经济体由于某种原因收缩了50%，如果它能够把产出恢复到收缩前的水平，那么即使只收缩50%，它也是在收缩后的基础上增长了100%。因此，假设在经济一旦恢复正常的情况下，2020年第二季度的GDP至少恢复到2019年第四季度的水平，这也不是不合理的。2020年第一季度的GDP比2019年第四季度下降了26.9%，2020年第二季度的GDP要想恢复到2019年第四季度的水平就必须环比增长36.8（26.9/（1-0.269））%。这很高，但并非不可能，因为它只说明收复了失地。如果第二季度GDP为27.80（20.32×1.368）万亿元，第三、第四季度分别预计为29.00（27.80×1.043)万亿元和31.98 （29.00×1.103）万亿元，则2020年全年的GDP预计将达109.1万亿元，比2019年增长10.1%。不过，如果2020年第二季度GDP为27.80万亿元的话，意味着当季的同比增长率达到14.6%，这似乎有点太高了。

另一个可供选择的假设是，2020年第二季度GDP将恢复到与2019年第二季度的24.26万亿元持平，当季增长率为19.4%，而不是36.8%。由此，预计2020年第三、第四季度GDP分别为25.30（24.26×1.043）万亿元和27.90（25.30×1.103）万亿元。基于这些推测，2020年的GDP预计为97.78万亿元，也就是收缩1.4%。

然而，到目前为止，所有关于内地重开和复苏的数据都表明，2020年第二季度GDP最可能的结果是同比增长6.0%，也就是说达到25.71（24.26×1.06）万亿元，这意味着环比增长26.5%。相应的，2020年第三、第四季度的GDP预计为26.82（25.71×1.043）万亿元和29.58（26.82×1.103）万亿元。这样，2020年全年的GDP预计为102.43万亿元，比2019年增长3.4%。不过，所有这些预测仍然是基于没有额外经济刺激的假设。

虽然全年增长10.1%可能显得过于乐观，收缩1.4%可能显得过于悲观，但2020年增长3.4%看来还是相当合理的。然而，所有预测都是基于没有新的经济刺激这样一种假设。如果有额外经济刺激，则内地经济当能在2020年的第三、第四季度以更高速度增长。如果我们假设有刺激经济的措施，2020年第三、第四季度的环比增速会比正常的增长速度高出25%，季度GDP将分别达到27.09（25.71×1.054）万亿元和30.58（27.09×1.129）万亿元。按照同比计算，2020年四个季度的实际与预期经注增长速度分别为-6.8%、6.0%、7.4%和10.0%。

如果把2020年各个季度的实际和预计GDP加起来，则2020年全年的实际GDP预计是103.70万亿元，比2019年增长4.65%，这是在有额外经济刺激的情况下。然而，正如上面所提到的，如果没有任何经济刺激的话，2020年的GDP增长速度有可能是3.4%左右。与此同时，如果全球其他经济体在第三、第四季度也出现复苏，那么中国的经济增长会更快，全年有可能超过5%，这也是在有额外经济刺激的情况下。当然了，在2020年剩下的时间里，中国内地经济复苏的速度究竟有多快，仍有待观察。我们的假设和预期是，在2020年剩下的三个季度里，中国经济的增长速度会大大高于正常水平。

In 2020Q1, there was an outbreak of the COVID-19 epidemic in China, which resulted in the temporary cessation of most economic activities in China due to the blockade of Hubei and Wuhan and lockdowns in many provinces and cities. Chinese real GDP declined by 6.8 percent, year-over-year, in the first quarter of 2020. A great deal of interest is focussed on the level of Chinese real GDP in 2020. The Chinese GDP in 2020 depends crucially on two developments—the speed of the economic recovery from the COVID-19 epidemic and the availability of additional economic stimulus.

In Table 1, the levels of Chinese quarterly GDP in 2019 prices since 2015Q1 are presented in both Yuan (column 2) and US$ (column 3) at the average Yuan/US$ exchange rate over 2019 of 6.9 Yuan per US$. In addition, the quarterly year-over-year as well as the quarter-over-quarter real rates of growth are also presented in columns 4 and 5 respectively. We note, first of all, that the Chinese quarterly year-over-year real rates of growth have been declining gradually over the years. Moreover, in 2019, Chinese economic growth slowed down significantly because of the then rising China-U.S. trade war, and continues to be adversely affected by it. Table 1 shows that the quarterly year-over-year rate of growth declined gradually from 6.4% in 2019Q1 to 6.0% in 2019Q4. If there were no COVID-19 epidemic in China, the 2020Q1 GDP would probably have been approximately 6.0% higher than the 2019Q1 GDP of 21.81 trillion Yuan, or 23.12 (21.81 x 1.06) trillion Yuan. This would be our estimate of the hypothetical 2020Q1 GDP. The actual 2020Q1 GDP was 20.32 trillion Yuan. Thus, the loss of Chinese GDP due to the COVID-19 epidemic may be estimated as the difference between the hypothetical and the actual GDP, that is, 2.8 trillion Yuan (US$405 billion), or 2.8 percent of the 2019 Chinese national GDP of 99.09 trillion Yuan.

However, a decline in Chinese GDP in the first quarter from the fourth quarter of the previous year is not unusual. An inspection of column 5 of Table 1 suggests that it occurs regularly, with an average non-annualised quarter-over-quarter decline of 16.9% between 2015 and 2019, but of course, not quite of the same magnitude as the decline of 26.9% actually realised in 2020Q1. Moreover, the first-quarter GDP typically accounts for less than 22 percent of the annual GDP, whereas the fourth-quarter GDP typically accounts for more than 28 percent of the annual GDP. This is due to the Spring Festival (lunar new year) holiday in China, which typically takes place between January and February, with all agricultural, manufacturing, mining and construction activities ceased.

The levels of Chinese quarterly GDP in 2019 prices since 2015Q1 are also presented in Chart 1. For 2020Q1, we show in the same column both the actual level (in solid colour) and the hypothetical increase (in striped colour) of real GDP, with the hypothetical increase being our estimate of the loss in national GDP attributable to the COVID-19 epidemic, 2.8 trillion Yuan. Chart 1 clearly confirms the pronounced seasonality in the quarterly GDPs observed in Table 1. In particular, the rate of growth between Q1 and Q2 (from green column to red column) is much higher than the year-over-year growth rate of Q2 GDP (from red column to red column). In fact, the average rate of growth of GDP between Q1 and Q2 is 11.4% over the past five years (see Table 1, column 5).

Thus, normally, 2020Q2 GDP is expected to increase by 11.4%[1] from 2020Q1, so that the 2020Q2 GDP may be projected to be 22.64 (20.32 x 1.114) trillion Yuan. The 2020Q3 GDP is expected to increase by 4.3%[2] from 2020Q2, to 23.61 trillion Yuan. The 2020Q4 GDP is expected to increase 10.3%[3] to reach 26.04 trillion Yuan. For 2020 as a whole, by adding the actual 2020Q1 and the projected 2020Q2, Q3 and Q4 GDPs together, we obtain a projected annual GDP of 92.61 trillion Yuan. This represents a decline of 6.5% from the 2019 GDP of 99.09 trillion Yuan, which seems excessively low. Moreover, these projections are all based on the assumptions that there is no recovery effect and there will be no additional economic stimulus in China.

A major weakness in the above analysis is its failure to take into account that in 2020Q2, it is a recovery to a previously achieved level of output and not a fresh round of new growth, and hence should be more rapid. Consider an economy which has contracted by 50%, for whatever reason, if it is able to restore its output to just before the contraction, it will have grown 100% from the shrunken base, even though the contraction was only 50%. It is therefore not unreasonable to assume that GDP will be restored to at least the level of 2019Q4 in 2020Q2, once things return to normal. 2020Q1 GDP declined by 26.9% from 2019Q4. In order for 2020Q2 GDP to recover to the 2019Q4 level, it will have to grow at 36.8 (26.9/(1-0.269)) % quarter-over-quarter in 2020Q2[4]. This is high, but not impossible, because it just represents recovery of lost grounds. With a 2020Q2 GDP of 27.80 (20.32 x 1.368) trillion Yuan, the 2020Q3 and Q4 GDPs may be projected successively as 29.00 (27.80 x 1.043) and 31.98 (29.00 x 1.103) trillion Yuan. This results in a projected GDP for the whole of 2020 of 109.1 trillion Yuan, or a rate of growth of 10.1% over 2019. However, a level of 2020Q2 GDP of 27.80 trillion Yuan implies a year-over-year rate of growth of the 2020Q2 GDP of 14.6%, which seems a little too high.

Still another possible alternative assumption is that the 2020Q2 GDP will recover to the same level as the 2019Q2 GDP of 24.26 trillion Yuan, a quarterly rate of growth of 19.4% instead of 36.8%. The 2020Q3 and Q4 GDPs can therefore be projected to reach 25.30 (24.26 x 1.043) and 27.90 (25.30 x 1.103) trillion Yuan respectively. These projections result in a projection of 2020 annual GDP of 97.78 trillion Yuan, implying a contraction of 1.4%.

Yet all the data on the re-opening and recovery on the Mainland to date suggest that the mostly likely outcome of 2020Q2 GDP is a year-over-year growth of 6.0%, that is, it would reach the level of 25.71 (24.26 x 1.06) trillion Yuan, implying a quarter-over-quarter rate of growth of 26.5%. The corresponding 2020Q3 and Q4 GDP's may be projected successively as 26.82 (25.71 x 1.043) and 29.58 (26.82 x 1.103) trillion Yuan. This results in a projected GDP for the whole of 2020 of 102.43 trillion Yuan, or a rate of growth of 3.4% over 2019. However, all of these projections are still based on the assumption of no additional economic stimulus.

While a 10.1% annual rate of growth may appear too optimistic and a 1.4% contraction may appear too pessimistic[5], a 3.4% annual rate of growth for 2020 seems quite reasonable. However, all of these projections are predicated on the assumption of no new economic stimulus. If there were additional economic stimulus, the Mainland economy should be able to grow at higher rates in 2020Q3 and Q4. If we assume that with additional economic stimulus, the Mainland economy can grow at a rate 25% higher than the normal quarter-over-quarter rates of growth in 2020Q3 and Q4 respectively, it results in projections of 2020 quarterly GDPs of 27.09 (25.71 x 1.054) trillion Yuan and 30.58 (27.09 x 1.129) trillion Yuan respectively. On a year-over-year basis, the actual and our projected rates of growth of the four quarters in 2020 are -6.8%, 6.0%, 7.4% and 10.0% respectively.

If we now sum up the actual and these projected levels of quarterly GDPs for 2020, we obtain a projection of 2020 real GDP of 103.70 trillion Yuan, or an increase of 4.65% from 2019, with additional economic stimulus. However, without any economic stimulus, the rate of growth of GDP for 2020 is likely to be around 3.4%, as we have seen above. If, in the meantime, the rest of the global economy also recovers in 2020Q3 and 2020Q4, the Chinese rates of growth would be even higher, perhaps even exceeding 5% for 2020 as a whole, with additional economic stimulus. Of course, it remains to be seen how fast the Mainland economy will be able to recover for the rest of 2020. Our assumption and expectation is that the rates of growth for the remaining three quarters of 2020 will be significantly above normal.