Population of China

China

World's Most Populated Country

China's population as of 2015 is 1.4 billion making it the world's most populous country. Using provided data demonstrating growth of China's population since 1960 we will select best equation which describes population growth until present day.

Table 1. Raw Data

Line 1 Years after 1960	Line 2 Population in Millions
0	667
5	715
10	818
15	916
20	981
25	1051
30	1135
35	1204
40	1262
45	1303
50	1337
55	1370

Provided data was loaded into a graphing calculator to perform regression analysis. Four different equation types were tested:

1. Cubic regression
2. Quadratic regression
3. Exponential regression
4. Linear regression

1. Cubic Regression Graph

Cubic Regression Equation:

y = ax³ + bx² + cx + d

y = -0.0024107744x³ + 0.0845532246x² + 15.53260813x + 656.3589744

Y-intercept: 656

Number of X-intercepts: 1

2. Quadratic Regression Graph

Quadratic Regression Equation

y = ax² + bx + c

y = -0.1143356643x² + 19.72132867x + 641.4423077

Y-intercept: 641

Number of X-intercepts: 2

3. Exponential Regression Graph

Exponential Regression Equation

y = ab^x

y = 717.0066508 ◦ 1.013448475x

Y-intercept: 717

Number of X-intercepts: 0

4. Linear Regression Graph

Linear Regression Graph

y = ax + b

y = 13.43286713x + 693.8461538

Y-intercept: 694

Number of X-intercepts: 1

Table 2: Pros and Cons

	Pros	Cons
Cubic	Fits most data points	Does not fit 2 data points
Quadratic	Fits 2nd most data points	Does not fit 4 data points
Exponential	None	Only fits 2 data points
Linear	None	Only fits 2 data points

China's Future Population

Predictions and Extrapolations

This data collected from a Wikipedia source shows that China's population is expected to begin declining by 2040.

Table 3: China's future population - data from Wikipedia source

Line 1 Year	Line 2 Population in Millions
2020	1387
2030	1393
2040	1360
2050	1295
2060	1211
2070	1125
2080	1048
2090	984
2100	941

Previously found Cubic Regression equation was applied to same Year points - 60 to 120 year after 1960. Resulting Population Data points can be found in table below.

Table 4: China's future population as predicted by my Cubic Regression equation

Line 1 Years after 1960	Line 2 Population in Millions
60 (2020)	1372
70 (2030)	1331
80 (2040)	1206
90 (2050)	982
100 (2060)	644
110 (2070)	179
120 (2080)	- 428
130 (2090)	- 1192
140 (2100)	- 2127

This data predicts a drastic decline of China's future population which does not fit statistical prediction obtained from Wikipedia source.

Next I applied previously found Quadratic Regression equation in the same manner. Resulting Population Data points can be found in table below:

Table 5: China's future population as predicted by my Quadratic Regression equation

Line 1 Years after 1960	Line 2 Population in Millions
60 (2020)	1413
70 (2030)	1462
80 (2040)	1487
90 (2050)	1490
100 (2060)	1470
110 (2070)	1427
120 (2080)	1362
130 (2090)	1273
140 (2100)	1161

This data indicates that China's future population will continue to increase until a peak in 2050 after which it will start to decline again. This is a reasonable prediction.

Conclusions

In years from 1960 to 2015 Chinese population has been increasing. According to various predictions China's population growth will slow down and reverse in future. Results of my Quadratic Regression (see Table 5) equation predicts this trend to reverse in 2050s with China's population begging to decline slowly. Results of my Cubic Regression (see Table 4) predicts China's population begging to sharply decline in 2020s. Lastly data obtained from Wikipedia source indicates that statistics predicts China's population growth to reverse in 2030s.

References

• China's population growth (Table 1): http://countrymeters.info/en/china See table: China population history
• China's future population (Table 3): http://en.wikipedia.org/wiki/Demographics_of_China See: Population Projection, United Nations 2010 estimate.