Posted by
Boreak Silk on
Oct 23, 2011; 10:34pm
URL: http://spssx-discussion.165.s1.nabble.com/Re-Survey-Sampling-Design-tp4924945p4930661.html
Hi Han,
Two issues that you need to address - technology and estimate. We are
doing a similar exercise in Melbourne but
in open space environment.
Technology - we tested various pedestrian counting sensors and
the most accurate, that we could get a few years ago,
are
thermal/laser sensors installed under awnings/on
public poles. Using these can address undercounting issue (many
people
entering shoulder-to-shoulder but counted 1) issue and
they have very high level of accuracy less than +/- 5 per cent in
open
space environment.
This leads to the second issue - estimate: to test the level of
accuracy, we do manual count every 6-12 months. We look at
the hourly patterns (we have
data
down to minutely intervals) for different days (weekday, weekend day
or special event day)
and select an hour during peak hours, an hour during off
peak hours for a typical weekday and typical weekend day, do manual
count and then compare with sensor count
during at the same time. By doing a similar
exercise, you probably can come up with
an adjustment factor for your data, for example, one count
is equal to 1.5 people or something like that. You need to graph
hourly
or half-hourly data for different days of the week and make
your decision, based on your local knowledge, to drop the first and
last hour or half-an-hour counts from your analysis to account for
employees working in the centre.
Another issue, at least with your system, is the same people might be
counted more than once. I assume people might get in and out
of your centre more than once and you need to factor this in your
analysis depending on how accurate you want the result to be.
Hope this
helps.
Boreak
Dear Lister
Numerous visitors and customers visit our
business center for shopping and sightseeing each day and we have installed a
camera system to record the times of the door open and door close (we call it
door count). Unfortunately, this number is not exactly what we want due to
following reason:
· Numerous
employees are working inside the business center. Once they enter and exit the
building, they are counted, which make door count
inflated.
· When people enter
the building in group, they are just counted as
1
· ….
We know how many
times the door have been opened/close each day, but we want to find out actually
how many people enter/exit the building. Is that possible to conduct sampling to
get a coefficient and adjust the dour count using the coefficient to get the
number of victors, and how can we conduct such a sampling? Any suggestion will
be highly appreciated.
Han Chen
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