Transactions by New or Returning Customers

Thank you. I had a feeling there was probably a simpler way.

This formula from you works for giving new or repeat for each stayID:

Stay ID of the first visit = CALCULATE(MIN(Transactions[StayID]),
             ALLEXCEPT(Transactions,Transactions[CustomerKey]))

Stay Type = if(HASONEVALUE(Transactions[Date]),
	if(
		COUNTROWS(
			FILTER(
				SUMMARIZE(
					Transactions,Transactions[CustomerKey],
						"EFGH",MAX(Transactions[StayID]),
						"IJKL",[Stay ID of the first visit]),
				[EFGH]=[IJKL]))
		>0,"New","Repeat"),BLANK())

I understand how it works. Just one question, why do you use if(hasonevalue(...)..)? I don't understand the need. 

As my ultimate goal was to have a count of stayID with new or old customers, I played with your formula some more and found this seems to work:

Stay Count New Customers= 
                    COUNTROWS(
                        FILTER(
                            SUMMARIZE(
                                Transactions,Transactions[CustomerKey],
                                    "EFGH",MIN(Transactions[StayID]),
                                    "IJKL",[Stay ID of the first visit]),
                            [EFGH]=[IJKL]))

I had to change from MAX(Transactions[StayID]) to MIN(Transactions[StayID]) as that would cause a wrong answer if the same Customer came back during the period. 

Thanks again.