I have a three year old boy at home and he's learned that one way to keep the conversation
going with an adult is to simply ask the question, "Why?"
I'll say "We're going to church this morning" and he'll say "Why?" I'll say, "Because it's
Sunday" and he'll say "Why?" At this point, I'm stumped. Why exactly is it Sunday today and
not Tuesday.
Or in the morning I'll point out that it's raining outside and he'll say "Why?" And I have
to struggle with an answer like, "When there is too much moisture in the air, it falls down
to the ground in the form of precipitation."
At work when people ask me to do something, I need to emulate my little boy and and ask
them why. Not in a hostile way, but to get them to talk some more so I can find out exactly
what they want.
Yesterday, someone asked me to compute a standard deviation.
Would you be willing to look at this attached chart and give me your advice on how
I can calculate the standard deviation of the amount of drug (dose) that a patient may
receive due to standardization compared to what is requested, please? For example, if a
prescriber wants to order 15 mg/kg of acetaminophen and the dose is standardized. What
is the standard deviation from what was ordered on average? Does that make sense?
She sent me a table showing standardized dosing for acetaminophen. For children, the
dosage is usually a certain amount per kilogram of body weight. But the medicine itself comes
in a discrete form, such as drops or tablets. The typical dose is 10-15 mg/kg, so a child
weighting between 12 and 22 kg might get 2ml drops where represents a target dose of 200 mg,
but at the extremes of the weight range could represent a dose as small as 180 (12*15) or a
dose as large as 220 (22*10). A child weighing 27.5 to 57.5 kg could get a tablet, and this
represents a standardized dose of 500 mg, but it could be as small as 412.5 or as large as
575. There are 12 rows in the spreadsheet just like this.
Now I could probably figure out how to do something that would produce a degree of
deviation from the norm or standard, but there's a very good chance that I will produce
something that is not quite what this person wants. So I wrote back and asked politely why do
you need a standard deviation? It's just a question to get someone to talk more about what
their goals are.
I try to do this a lot. If they want to match subjects based on age and race, I'll ask
them why they think matching is important. If they respond, I thought you had to match or the
study wouldn't be valid, then we can talk about the various ways of ensuring validity of a
research trial. Asking why always seems to start a productive dialog.
I have a great quote on one of my web pages which is worth repeating here because Dr. Cox
explains this far better than I could:
The statistician who supposes that his main contribution to the planning of an
experiment will involve statistical theory, finds repeatedly that he makes his most
valuable contribution simply by persuading the investigator to explain why he wishes to
do the experiment, by persuading him to justify the experimental treatments, and to
explain why it is that the experiment, when completed, will assist him in his research.
-- Gertrude M. Cox.
This web page was written and was last modified on
09/24/2007.
