Group immunity refers to the resistance of human or livestock groups to infection. A high level of group immunity means a high proportion of animals resistant to infection in the group. Because the possibility of epidemic disease depends not only on the number of resistant individuals in the animal population, but also on the contact frequency between individuals in the animal population. What if there are 70% in the group? If 80% of animals are resistant, there will be no large-scale outbreak.
In fact, this is purely a cognitive paradox.
And after the vaccination, this kind of news will make a small comeback. In fact, this kind of news is far more common than we thought, just because our channels are not enough, and the influence of these news is not enough to spread to everyone.
Not only that, but also put forward the use? Group immunity? Most people, including those who come to deal with it, don't know that there is such an incomprehensible fact:
Even if a few people are vaccinated, the ultimate victims are not the majority who are not vaccinated, but those who are vaccinated, or newborns and immunosuppressed people who cannot be vaccinated.
So the vaccine is really useless? Do you really have to sacrifice on a certain scale in exchange for the final immunity of the group?
The answer is definitely no.
This is actually the difference between medicine and mathematics. Mathematics is much more accurate than medicine, and medicine can't guarantee that treatments suitable for everyone will be useful for individuals. Mathematics can be inferred.
Why do you advocate vaccination or collective home isolation?
It is to cut off the way the disease spreads from person to person, so if most people can be vaccinated or not exposed to the disease and cut off the spread, then even if a few people can't, it can still be controlled; On the other hand, the efforts of a few people are definitely not enough.
Moreover, the above process is only a simple linear inference, and the risk of infection is likely to increase exponentially.
So, we should at least be able to draw a correct conclusion:
When very few people are exposed to risks, on the whole, it is safe for at least most people who control risks; On the other hand, most of them are in danger, which is not good for both sides and nothing can be done.
Therefore, in fact, it is not difficult for most people to understand this process as long as they have this basic mathematical thinking ability or have appropriate channels to spread this idea.
The above example is selected from the Italian mathematician and IT expert Maurizio? Codogno's interesting popular science book "Talking about Mathematics at Lunch Time" is only two or three pages, but he used measles and whooping cough cases in the United States for analysis.
So, when I was at school, it was widely circulated? Learn math, physics and chemistry well, and you are not afraid to travel all over the world? Actually, it really makes sense.
We don't need to know all kinds of theorems, inferences and solutions like academic research, but we can improve our logical thinking ability through necessary common sense understanding, so as to analyze and draw conclusions more rationally.
These two portable and lovely pocket books "Talking about Mathematics at Lunch Time" and "Talking about Mathematics at Coffee Time" are the most convenient, easy to understand and interesting ways, which can solve some of the fear of difficulties when talking about mathematics and try to get in touch with these interesting common sense that we should know.
(2) What phenomena in life can profound and obscure mathematical principles help us understand and correct stereotypes?
1. chart instead of data and text description is easy to cause understanding deviation?
In our daily work, we are always used to showing the contrast and difference of a set of data in the form of pictures or charts in the report.
It brings simplicity and convenience at a glance, but in fact, there is a deviation between the information that everyone understands, the information reflected in the chart and the real information that cannot be ignored.
First, whether it is a bar chart, a bar chart or other beautiful graphics, it is essentially a one-dimensional image. Such a chart makes sense only when the data shows a linear growth trend.
For example, reflecting the impact data of oil spill, the spread area is more suitable for two-dimensional graphics such as circles and squares, and whether the past reports can fully reflect the seriousness of the data simply by using bar charts.
Second, limited by a large number of data, the charts we made fully reflect our purpose. This incomplete chart itself highlights some part of the information, but not all of it.
For example, when the difference between the data and the overall comparison is very small, it is almost the default to take a certain value as the starting point and artificially enlarge the difference.