March 2010

Confusing metrics: Unique visitors, visits, time spent

Dana Chinn

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Unique visitors

visit websites,

generate page views.

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A “unique visitor” is actually a “unique computer”

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Work

Home

Hotel

= 3 unique visitors

Unique visitors may be over- or undercounted

= 3 unique visitors

Work

= 1 unique visitor

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The no. of unique visitors is based on the time period you specify.

S M T W Th F S

31

July 6-12

1

...on Tuesday, July 1, is six...on Friday, July 4, is three

July 13-19

July 20-26

The number of “daily unique visitors”

July 27-31

532 4

6

S M T W Th F S

31

July 6-12

1

...for the week of July 6-12 is six

July 13-19

July 20-26

The number of “weekly unique visitors”

July 27-31

7

S M T W Th F S

31

July 6-12

1

...for the month of July is seven

July 13-19

July 20-26

The number of “monthly unique visitors”

July 27-31

532 4

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Daily UV counts can’t make weekly UVs,weekly UVs can’t make monthly UVs, etc.

SMTWThF

Sa

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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

Don’t waste time on “time spent on site”

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“Time spent” isn’t a useful metricbecause it doesn’t indicate engagement

...and the way it’s calculatedis really ugly

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Bounces are included as zero, or no time - but the visitor could have indeed been actively looking at the page

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.

The amount of time a visitor spent on the last page view isn’t included

“Time spent” is:

The total time in between a visitor’s first page view and the visitor’s last page view

...which means

Flash, other dynamic content isn’t counted as a page view

Also see http://www.newsnumbers.com/2010/03/wasting-time.html

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Dana Chinn Lecturer chinn@usc.edu 213-821-6259

Analytics for news orgs bookmarks http://www.delicious.com/danachinn

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Twitter: DanaChinn

Blog http://www.newsnumbers.com