$$The use of $$sensitivity analysis thinking$$ is a key technique to ensure that this backward calculation approach delivers an appropriate model: in practical terms, this means that when designing models, one should define as early as possible the specific sensitivity questions that will need to be addressed once the model has been completed$$ Rees, $(2015$: $147)$

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$6\mathrm{.}1$ Analyse and discuss sensitivity analysis. $(10$ marks$)$