From: tnguyen@oasys.dt.navy.mil (Thang Nguyen)
Newsgroups: soc.culture.vietnamese
Subject: Re: Embargo & Normalization ( second poll )
Date: 21 Jul 92 17:14:14 GMT
Reply-To: tnguyen@oasys.dt.navy.mil (Thang Nguyen)
Organization: Carderock Division, NSWC, Bethesda, MD

Dear SCV netters:

I have a few more technical comments about the polls posted by anh Ddi.nh.
First, I think the second approach (calling up the interviewees) is
a much better approach. Second, the results of the two polls are comparable
(percentage-wise).

However, there still are a lot of technical issues that need to be addressed.
if a poll is to be scientific.  I will list only a few examples of the
technical details that should be taken into consideration in the design
of a poll.

1. Is random really random?
   Random pick is not random. Randomly catching mice in a cage will
result in a bias in favor of those who are fat, slow, and lazy (the
strong and more active ones would have eluded the catch.)
   Without careful design, a seemingly random poll would be actually
very biased. Those who are quick to pick up the phones might be the
ones who are very active in the community or they might be teenagers
who cannot live without a phone. One way to avoid this kind of bias
is to use "last birthday" approach in the sampling: just ask for the
one in the household who got the last birthday (it's easier to recall
who had the last birthday than who will have the next birthday in the
house.)
   The time of the calls can create biases as well. If calls are made
on weekdays in the day, the sample will be biased in favor of the elderly,
housewives, the unemployed... Each time in the day has an inherent bias.
The best time is probably between 4:30 and 8:30 PM.

2. Is the interviewer well trained?
    Voice intonation, leading remarks, and the overall conduct of the
interviewer has substantial impact on the response of the interviewee.
A common behavior is to play along. The interviewee tends to accommodate
the interviewer based on perception of the latter's motive or goal.
Without careful training, an interviewer might ruin the entire polling
effort.

3. Are the questions well posed?s
   Of course, a serious poll taker should shoo away ambiguous and leading
questions. However, a well-posed question requires much more. Just one
example: I notice that there is a need for a fourth choice in the poll
reported by anh Ddi.nh, namely, "don't want to answer". This is very
much different from "don't know." The latter indicates that the
interviewee has no opinion while the former indicates that he/she has
an opinion but does not want to disclose it.

Of course, there are many more issues. For instance the issue of unlisted
phone numbers, the issue of no-responses (hang-ups, not at home, busy
line...) If all calls are responded, that will cast some doubt about
the sampling technique.

There are a number of good books on phone surveys for those who are
interested.

As a final note, I wouldn't blame the TV Program in San Jose if the
poll falls short of being scientific. Its raison-d'e^tre is not to conduct
scientific surveys but to broadcast TV programs. However, I stress the
need to have scientific surveys on numerous aspects of life in our community.
These surveys have been lacking for the past 16 years.

Cordially,
Thang.
Newsgroups: soc.culture.vietnamese