Just one question: If one question works, why ask several?

While shorter instruments are more limited than longer measures, they have obvious benefits for both research and policy in terms of reduced burden and costs, and ease of interpretation.

A frequently asked question by clinical investigators is why they should use a lengthy, multi-item measurement scale to assess patients’ perceptions of their health, or quality of life, when there is evidence that a measure containing a single, global question is likely to suffice. Researchers may not wish to use lengthy scales because their core questionnaires are already long, the patient group of interest is ill or frail, they wish to minimise the burden on the patient and on the research team, or they simply want a “snap shot” of a topic rather than comprehensive coverage. In such circumstances, single questions have the obvious advantage of brevity, of making fewer demands than multi-item measures on respondents and researchers. Single, global questions have long been used in population surveys to measure health status, quality of life (QoL), and health related quality of life (HRQoL). The two most popular single global health items are self rated health status and self reported limiting, longstanding illness.

 BY: Ann Bowling

Please follow this link to read more:

http://jech.bmj.com/content/59/5/342.full

 if the variable depends on only one factor it is possible to mange within one questions,But I am wondering whether it is scientific / natural

Well, honestly said, it is not one question which measures a variable, but rather the answer to that question. The question is to be ver well set out, of course.

A simple answer to a question can be either yes versus no, ignoring 'yes' but..... or 'no' but? The question therefore has to be very precise, e.g. do you wish to participate at an event?

Variables are defined by both model (concept) and operation (mode of measurement). All research questions have a dependent variable. However, sometimes a research question is not simply interested in measuring the dependent variable in its entirety, but a particular component of the dependent variable. So, how the dependent variable is written out in a research question and what you call it are often two different things. I agree with Dear Carlos - "not one question which measures a variable, but rather the answer to that question."

Just one question: If one question works, why ask several?

While shorter instruments are more limited than longer measures, they have obvious benefits for both research and policy in terms of reduced burden and costs, and ease of interpretation.

A frequently asked question by clinical investigators is why they should use a lengthy, multi-item measurement scale to assess patients’ perceptions of their health, or quality of life, when there is evidence that a measure containing a single, global question is likely to suffice. Researchers may not wish to use lengthy scales because their core questionnaires are already long, the patient group of interest is ill or frail, they wish to minimise the burden on the patient and on the research team, or they simply want a “snap shot” of a topic rather than comprehensive coverage. In such circumstances, single questions have the obvious advantage of brevity, of making fewer demands than multi-item measures on respondents and researchers. Single, global questions have long been used in population surveys to measure health status, quality of life (QoL), and health related quality of life (HRQoL). The two most popular single global health items are self rated health status and self reported limiting, longstanding illness.

 BY: Ann Bowling

Please follow this link to read more:

http://jech.bmj.com/content/59/5/342.full

Most of scientific problems depend on a lot of parameters as well as the results and answers. I think we need very precise questions with clear definitions, not only one variable.

http://privatewww.essex.ac.uk/~scholp/onevardesc.htm

Thanking you @KU Sir interesting question

Good research question it helps in your variables and co-variables. Definitely it possible other wise research may not be existed Sir.

Thanking you 

Yes it can,  but why you restrict your self. Many  questions can  be measured then why  only one?

Dear Mahfuz,

For a univariate statistical study, it is sufficient only one question.

Thanks for sharing. Yes, the evaluation of a variable is possible by asking only one question.

Regards

Dear Mahfuz:

Some variables can be measured with just one question. Take, for example, the widely used single question to measure Interpersonal Trust, which was devised by Elizabeth Noelle-Neumann in 1948 and has been applied since then:

"Generally speaking, would you say that most people can be trusted or that you can't be too careful in dealing with people?"

This is a dichotomous variable: Most people can be trusted / Can't be too careful. 

When the variable is multidimensional, however, we need more than one question. An example is Socioeconomic Status (SES), which includes at least education, income and occupation.

Sometimes, although we can measure a variable with just a single question, it may be preferable to use two or more items, because this improves reliability.

Yes, if we compare the estimation done after asking with the ignorance on hand if we do not ask.

But there exist seceral issues on how accurate our estimation will be... a whole science.

If the variable is a simple fact, then a simple question will do : "do you have a fulltime working contract ?", "did you ever get epidural anesthesia ?". If the variable envolves some kind of evaluation then a simple question won't do : "are you a safe driver ?".

I believe, we may use one question with a variable and some statistical analyses can be performed. At the same time, some other statistical analyses are difficult to be utilized such as factor analysis and structural equation modeling.  

there are lot of research studies that have measured a variable with one question only e.g. job satisfaction, . But response to one variable construct is not taken as reliable especially in behavioural sciences

Probably it 'depends' how you consider the 'variable'.

How are variables measured?

http://www.indiana.edu/~educy520/sec5982/week_3/measurement_rsm.pdf

Variables And Measurement Scales

http://www.slideshare.net/guesta861fa/variables-and-measurement-scales

The questionnaires questions must past through "the filter question", that make the researcher think about the variables and the aspects of his research.

What is your aim and objectives? Are you following the correct variations in your study

is important first then focus your question straight forward.

Thanking you

I do agree with your statement too.

 Dear Dr. Srinivas,

I have read all answers to your question on what was the Maximum Number of Items that a Construct could have. The question and its answers were very useful and interesting.

Regarding Hinkin`s (1995) statement that scales with too many items can create problems with respondent fatigue or response biases. I agree with the first part regarding creating problems with respondent fatigue, but, I would like to say that one question, and not too many questions, can cause response biases.

How are variables measured?

Please see the following file>

Regards

The Measurement of a variable with one question looks like checling and no stable. The sure mentioned should encompass all facets of the variable.

Sorry for typing mistakes 

It depends on the variable.There are variables with yes/No answers which can be measured by one suitable questiobn

Regards,

The variable is measured with the observation or response to the question. If we know the response to the question in all the population units, we know the searched variable.

Since factor analysis is a statistical procedure that is conducted to identify groups of related items, do we have to consider factor analysis output in this regard?  

It the answer is the measure of the variable in a unit, yes, we can do it.

Yes, Variables And Measurement Scales

Best Regards Nishad.

We can measure a variable with the observation of the response or answer to a question or with the physical measure of the variable.

Why not, its depend on researcher need. If researcher achieve objectives and goals with one question or variable surely he can do it. Ex. In satisfaction survey salary or reward for work one gets from his work.

A variable can be measured with correction with the true answer to a question. If the answer is not true, the measure would be incorrect and would not serve to measure the variable in truth.

I agree with Professor Mariano that if the answer is not true, the measure would be incorrect.

 https://en.wikipedia.org/wiki/Questionnaire

It will be a very focused question and the variable will  be dealt with in depth and breath.

Human creativity has no limit.Why not a a single question to measure a variable ? The answer may be yes or No or similar to that, when the question leaves nothing to imagination!

Regards,'Dr.K.R.Subramanian

Good answer by Dr @ Seyed Mehdi Mohammadizadeh.

Yes. If the variable is something like your height!

That depends from open minded of the examinee.

Depends on the variable and the population.