The idea of crossover comes from the crossover method in mathematical operation, which is mainly used to solve the problem of ratio mixing, such as average mixing, concentration mixing and discount mixing. , indicating that the overall proportion is between two parts and tends to the part with large base. The most common problem in data analysis is the growth rate, and the growth rate will also have the problem of mixed growth rate, so the cross idea in data analysis refers to the mixed growth rate between the two growth rates before mixing, and the value is biased towards the growth rate of the data with large base period value. Let's take a knife as an example to analyze it.

For example, in 20 13 years, the total social logistics in China was 197.8 trillion yuan, which increased by 9.5% year-on-year, and the growth rate dropped by 0.3 percentage points over the previous year. Quarterly, 1 increased by 9.4%, by 9. 1% in the first half of the year, and by 9.5% in the first three quarters, showing a trend of "stabilizing and slowing down" to "stabilizing and rebounding".

20 13 years, the quarter with the highest year-on-year growth rate of total social logistics in China is ().

A. first quarter B. second quarter C. third quarter D. fourth quarter

Answer C. Analysis: The year-on-year growth rate in the first quarter was 9.4%, and that in the first half was 9. 1%. The mixed growth rate in the first and second quarters was between double digits, so the growth rate in the second quarter was less than 9.4%. The growth rate in the first three quarters was 9.5%, which was a mixture of the growth rate in the first half and the third quarter, so it was greater than 9.5% in the third quarter; The annual growth rate is 9.5%, which is a mixture of the growth rates in the first three quarters and the fourth quarter. It was 9.5% in the first three quarters, so it was 9.5% in the fourth quarter, so the year-on-year growth rate in the third quarter was the highest. The answer is C.

The most important thing is to analyze who is the mixed quantity and who are the two quantities before mixing. Then, according to the mixed growth rate between the first two growth rates, the answer is judged by combining options.