On a weekly AAPL chart I have an ATR of 1.83 but the stock has moved about 20.00 over the past week.  Do I interpret the 1.83 ATR as a $18.00 move?

The trainers can't give setting, interpretation or investment advice, but I can explain how Average True Range (ATR) is calculated.

True Range is the True High minus the True Low.

The True High is the higher of the previous Close and the current High.

The True Low is the lower of the previous Close and the current Low.

So the True Range is the range of the stock including the span since the previous close (so it the range plus any gaps).

Average True Range is just a Moving Average of True Range.

Note that on a Weekly Chart, I currently have a 14-Period Average True Range (ATR) of 22.76. Note that this is based on Calender Weeks. So the first thirteen True Ranges included in the calculations are full calendar weeks, but the current True Range only includes the the range of today plus any gaps between today's range and Friday's close.

As a rule of thumb ATR are calculated on Daily / weekly   ... what is the time period that most traders would have it set on   .... can you set alerts for stocks based on ATR

Thanks in advance

I do not know what time period most traders might use. Even if I did, the trainers can't give setting, interpretation or investment advice.

If you add the Average True Range Indicator to the chart, you can click on it and select Set Alert to create an Alert in the same way you can for most indicators.

Setting Alerts
Monitoring Alerts