This document discusses several metrics used to measure website traffic, including unique visitors, visits, and time spent on site. It explains that (1) a unique visitor counts each computer that visits rather than each person, (2) unique visitors may be over or undercounted depending on how many devices a person uses, and (3) the number of unique visitors depends on the specified time period. It also discusses that (1) a visit is defined as activity separated by 30+ minutes of inactivity, (2) time spent is a flawed metric that does not indicate engagement.

1. Confusing metrics:
Unique visitors, visits, time spent
Dana Chinn
March 2010

2. Unique visitors
visit websites,
generate page views.
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3. A “unique visitor” is actually a “unique computer”
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4. Unique visitors may be over- or undercounted
Work =33 unique visitors
= unique visitors
Hotel
Home
= 1 unique visitor
Work
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5. The no. of unique visitors is based on the time period you specify.
S M T W Th F S
1 2 3 4 5
July 6-12
July 13-19
July 20-26
July 27-31
31
The number of “daily unique visitors”
...on Tuesday, July 1, is six
...on Friday, July 4, is three
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6. S M T W Th F S
1
July 6-12
July 13-19
July 20-26
July 27-31
31
The number of “weekly unique visitors”
...for the week of July 6-12 is six
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7. S M T W Th F S
1 2 3 4 5
July 6-12
July 13-19
July 20-26
July 27-31
31
The number of “monthly unique visitors”
...for the month of July is seven
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8. Daily UV counts can’t make weekly UVs,
weekly UVs can’t make monthly UVs, etc.
S
M
T
W
Th
F
Sa
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9. The math of visits
A visit is a period of activity separated by
at least 30 minutes of inactivity.
A visitor clicks into your site at 1 p.m., surfs for 20 minutes, then clicks into CNN.com.
One visit
A visitor clicks into your site at 1 p.m., surfs for 45 minutes, talks
on the phone for 30 minutes without touching the keyboard, then
hangs up and goes back to your site for 20 minutes before
clicking into CNN.com.
Visit 1: 45 minutes Visit 2: 20 minutes
Two visits
A visitor clicks into your site at 1 p.m., surfs for one hour, leaves
his computer for 29 minutes, and then comes back and surfs for
another hour before clicking into CNN.com.
Visit time: 2 hours, 29 minutes
One visit
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10. Don’t waste time on “time spent on site”
“Time spent” isn’t a useful metric
because it doesn’t indicate engagement
...and the way it’s calculated
is really ugly
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11. “Time spent” is:
The total time in between a visitor’s first page view
and the visitor’s last page view
...which means
The amount of time a visitor spent on the last page view isn’t included
Bounces are included as zero, or no time - but the visitor
could have indeed been actively looking at the page
Flash, other dynamic content isn’t counted as a page view
You really don’t know the time truly spent. If a visit is
counted at 29 minutes, you don’t know if the person was
truly on the site for all 29 minutes or if he/she walked away
between minutes 1 and 28.
Also see http://www.newsnumbers.com/2010/03/wasting-time.html
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12. Dana Chinn Blog
http://www.newsnumbers.com
Lecturer
chinn@usc.edu
213-821-6259
Analytics for news orgs bookmarks
http://www.delicious.com/
danachinn
Presentations
http://www.slideshare.net/
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Twitter: DanaChinn
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