Valid reasons for not using a statistical method may include

the participants have not provided sound and sufficient reasons for withholding the information concerned.

There is seldom any excuse justifiable reason for abortion.

But then I found that he was held for an unrelated reason.

10 reasons for using video surveillance in your home

The participant can not refuse them without valid reasons.

10 reasons for using video surveillance in your home

There is seldom any justifiable reason for abortion.

The participant may not refuse without valid reasons.

These birds also regularly die without apparent reason.

Acknowledge that the person on the other side may have valid reasons.

In the absence of good grounds for belief he will be satisfied with bad ones”.

However, I am not sure what the exact reasons were??...

There are a bunch of reasons not to like this movie.

There are some valid reasons to use static methods: