First time and Repeat visitors not summing up as expected?

[asdf12341z]

Hello,

I am trying to understand the proportion of visitors to my site that complete a booking form that are:

first time visitors vs repeat visitors

I have a fallout chart for my visitors who have started an engagement with the booking form and then completed it. The number I get is 2,700 visitors, and the segment is defined as:

A Hit containing the URL of my webpage.

To understand the difference in-between first time and repeat visitors to my website who are completing this booking form, I add two more segments:

1) First time visitors: HIT containing the URL of my webpage AND Visit Number = 1

2) Repeat visitors: HIT containing the URL of my webpage AND Visit Number is greater than 1

For the first segment, I am getting 1989 visitors who completed the booking form and for the second segment I am getting 1453 visitors who completed the booking form. 

Evidently, the sum of these two numbers 3442 > 2700, but I do not understand why it isn't the same and why there seems to be some doubling up in the counting.

Here is an example of how the original segment is defined:

and how the "First time visitor" segment is defined:

Any help is appreciated.

Thanks!

[yuhuisg · Accepted solution]

One simple reason could be that you're using a "Visitor" scope for your fallout.

Recall that a visitor can have many visits. So depending on your date range (or even within the same day!), the same visitor could be both Visit Number = 1, i.e. had a first visit, and Visit Number != 1, i.e. had a return visit.

As a result, you can't simply add the Visitors metric from the 2 fallout charts. Instead, you have think of the two charts as a venn diagram, where there is an intersection between the two charts' data indicating Visitors who have had both first and repeat visits within the date range of your report.