Question about Scat Mats

Has anyone tried using a Scat Mat to deter their kitty(ies) from going outdoors? If so, was it effective?

Our new kitty Eve is 2 1/2 years old and quite used to being outdoors whenever she pleases. She is very strong minded and difficult to keep indoors when she decides she wants out. Previously she was indulged with a cat door which has contributed to her thinking it is her right to have outdoor privileges unattended.

She is gradually spending more time indoors with us and is always in at night. I am not comfortable with her being outside 'unsupervised' and would love to find a safe, effective way to encourage her to stay inside. My previous kitties were both indoor cats all their lives; I am not experienced at dealing with this problem.

Your thoughts and suggestions would be appreciated. Thank you for listening.

Betty