Far as I can tell, someone wrote:
>I had given her one of those probe thermometers

An oven I had several years ago was actually fifty degrees low. If you
simply pull the adjustment knob off the front of the oven, you will
probably see that it is marked inside to be adjusted.

You're right. The probe won't be accurate.
It would cost less than a good piece of meat to buy or borrow a
standing/hanging type thermometer and check the oven. You would also
learn that different areas or the oven are different temps. And you
could use it to see how quickly the temp rises or drops.

If you're serious about baking, (or even just don't want to ruin good
food,) knowing that your oven temp is accurate, and knowing when it is
actually ready to bake/roast, you need one.