Question

Sir William Blackstone (1723dash1780) wrote influential books on common law. He made the statement "All presumptive evidence of felony should be admitted cautiously; for the law holds it better that ten guilty persons escape , than that one innocent party suffer ."

Keep in mind that the null hypothesis in criminal trials is that the defendant is not guilty. State which of these errors (in bold) is the first type of error (rejecting the null hypothesis when it is actually true) and which is the second type of error.

Answer 1

The null hypothesis is

• 

Type I error is when we reject the null hypothesis when it is true. In this case let us say the defendent is not guilty, but if the defendent is wrongly convicted then we would be committing a type I error

So the statement one innocent party suffer

means that we have committed a type I error by convicting an innocent.

We commit a type II error when we accept a null hypothesis which is false. In this current context, we would be committing a type II error if we wrongly let go a defendent who is actually guilty.

The staement "ten guilty persons escape" is a case of committing type II error as we are wrongly letting go persons who are guilty.

Sir William Blackstone is of the opinion that it is better that we commit a type II error and let ten guilty persons escape, than commit a type I error and one innocent party suffer