On Tue, 21 Mar 2017 10:21:55 -0700, sms
wrote:

On 3/21/2017 7:31 AM, wrote:
On Monday, March 20, 2017 at 7:42:32 PM UTC-7, John B. wrote:

Unfortunately it does not conceal the fact that what you stated, "a
comparison of bike lights versus no bike lights", was not what the
Odense study tested, nor was it the results of the study.

But John, the whole point is that you have NO IDEA what they accomplished with a study that so obviously had such a small study group that they wouldn't even publish the size of it.

You know that in statistical analysis concerning small percentages of injuries and fatalities as bicycle accidents that the study size has to be gigantic to reveal any pertinent information. So why would you pretend differently?

You do realize how statistical sampling works don't you?

The study had 4000 participants, 2000 with the lights, 2000 without the
lights https://books.google.com.au/books?id=LvthAgAAQBAJ&pg=PA168.

This is an _enormous_ sample for a country of that size.

Denmark has about 4 million residents of cycling age. About 55%, or 2.2
million, cycle. The study had 4000 participants, 2000 with lights and
2000 without lights.

This would produce a result with a 2% margin of error and a 99%
confidence level. Even if 100% of those of cycling age cycled, the
sample size needed barely goes up.

Whatever criticism you may have of that particular study, sample size
cannot be one of them!

Nope.

The facts a

According to the Bicycling Embassy of Denmark, 9 out of 10 Danes own
bicycles, while only 40% own cars. 17% of all trips are by bicycle and
20% of all commuters travel by bicycle, on the average, Danes cycle
1.5 km a day, 44 % of all children aged 10-16 cycle to school.

The population of Odense is some 175,245 and:
31% of all people visiting the city center of Odense arrive by
bicycle.
Bicycle traffic constitutes 24% of all traffic.
Odense has more than 545 km cycle lanes.

There are some 26,000 students in Odense University, and if the same
parentage of collage students cycle as does the 10 - 16 age group
there are 11,000 cyclists in the University, of whom, apparently, some
36% participated in the study.

In short a country where bicycling is not only an accepted form of
transportation but a very, very, commonly used form of travel.

Given that from what I read Reelight gave a set of lights to each of
the 2,000, "with permanently on light" participants in the study I
don't find the numbers to be especially astonishing.

Another point. All bicycles in Denmark ridden after dark must, by law,
be equipped with a white headlight and a red rear light. Failure to
comply with this law results in a 700 Kroner fine. Given the heavy use
in Denmark I would suggest that all, or nearly all bicycles are
equipped with lights.

As far as I can tell 700 DKK is about 20% of the average monthly
salary.

This would produce a result with a 2% margin of error and a 99%
confidence level. Even if 100% of those of cycling age cycled, the
sample size needed barely goes up.

Whatever criticism you may have of that particular study, sample size
cannot be one of them!

I see nothing wrong with the study. The objection was the definition
of it as a study of bicycles with lights and those without lights.
Which was.... just not true at all.

Now, I see, the story has been changed and the lights/no lights story
has morphed into a whole new story.

Very adroit footwork I must say.
--
Cheers,

John B.