What are opinion polls and how are they conducted?

An opinion poll is a human research survey of public opinion from a particular sample of respondents from a population.

Polls are designed to represent the opinions of a population by conducting a series of questions and then extrapolating the findings to the entire population in ratio with the given results.

This survey – the National Public Opinion Poll on 'Panama Leaks Issue' – conducted by Gallup Pakistan was carried out according to the European Society for Opinion and Marketing Research (ESOMAR) Code of Ethics and internationally recognized principles of scientific polling.

All opinion surveys follow a set sample profile, which may vary from poll to poll.

This survey was carried out among a sample of 1,707 men and women statistically selected and comprising of a cross section of age, and socio-economic classes from the rural and urban areas of all the four provinces of the country, during May 30 and June 6, 2016.

According to detailed methodology provided by Gallup Pakistan, 39 percent of the respondents were under 30 years of age, 54 percent between 30 and 50 years, and eight percent above 51 years of age. 29 percent of households surveyed were from low-income groups, which are categorized as households with up to Rs 7000 monthly incomes. 47 percent of households surveyed were middle-income, i.e. they earn monthly incomes of between Rs7000 and Rs 20,000, while 16 percent were high income families earning over Rs20,000 in a month.

67 percent of the respondents belonged to rural areas while 33 percent were from urban area, with the majority from Pakistan’s most populous province Punjab (58pc), 24pc from Sindh, 14pc from Khyber Pakhtunkhwa, and the remaining 5 percent from Balochistan.

A key term used in opinion polls is margin of error—a probability number that expresses the amount of possible error in a survey's result that may arise from random sampling. The less the margin of error, the more confidence one can have that the poll's reported results are close to the true figures if the entire population was questioned.

The error margin in this particular poll was estimated to be approximately 3 to 5 percent at 95 percent level of confidence.

According to Gallup Pakistan, while samples are carefully selected from the population, interviewers are briefed to conduct the surveys following an ethical code of conduct and maintaining neutrality in asking questions from the respondents.

After the briefing is completed, all field workers conduct mock calls under the direct supervision of an executive or a fieldwork supervisor to ensure that the field workers properly understand the instructions and they can handle various interviewing problems during interviews in the field.

After completion of training, interviewers go into the field for actual interviewing.

After the surveys are completed, they are rechecked, verified, and coded to be entered into computers.

Gallup Pakistan says it uses the statistical computer program SPSS to enter data and analyse it to arrive on the survey results, which are presented in a final report format.