What different models have been used to calculate this and why have there been so many different forecasts? Which models are the most reliable ones and why?

Modelling the spread and the death rate of the coronavirus

Modelling the spread and the death rate of the coronavirus: What different models have been used to calculate this and why have there been so many different forecasts? Which models are the most reliable ones and why?

NB! The introduction need to fulfill the below criteria to 100%, please read carefully:
– Say exactly what the paper examines and what type of math that will be used. Specify clearly which mathematical rules that will be used
– A clear hypothesis
– A motivation for doing this, why it is important to understand
– Which data that will be used
– What mathematical software that will be used, if any