signal quality index and signal strength relation

Hi I am confused about the concept of signal quality index. what is signal quality index? what is the relation between signal quality index and signal strength? can we determine signal strength from signal quality index?

Quality is the related with the error rates whereas the strength is not directly related with the error but with the strength of the carrier and the depth of modulation. Both are independent but are conceptually related.

Thank you for your answer. I am actually working on a project and I need to calculate the signal strength from signal quality index. Can you please tell the definition of signal quality index and is there any equation that relates both? If you could suggest me any reference book it would be great for me.

This might have to do with the 5 descriptors used by ham radio operators. Each refers to some aspect of radio reception. '5' means perfect. '1' means unreadable.

'5 by 5' means ideal in all aspects.

https://en.wikipedia.org/wiki/Five_by_five