KARACHI, Feb 20: A seminar on “Understanding the Importance of Opinion Polls and Surveys” was organized by the Pakistan Press Foundation (PPF) in Karachi on Wednesday at its Vicky Zetlin Media Library.
Sibgatullah Hussaini, general manager Gallup/ BRB, explaining the methodologies of surveys, said: “we select the respondents in our surveys through random probability sampling, viz each member of the universe is given equal chance of being selected”.
He said the entire urban Pakistan was divided into primary sampling units of blocks of 200 to 250 households and each block was given an identification number. Likewise 45000 villages of Pakistan were treated as 45000 PSU’s.
“We instruct the computer to randomly select the PSU’s — from each province, district, Tehsil or union council. Once we randomly select the PSU’s, then we randomly select one household in every selected PSU,” he explained.
He said in each randomly selected household, all individuals above a certain age were listed and one of them was randomly selected through the KISH method and he/ she was interviewed.
“Then the random walk starts and we leave three houses on the RHS and knock the fourth door and repeat the process,” he said and added that Only 10- 15 interviews were conducted in each PSU and the responses were then coded and entered into computers.
He said the results were reweighed according to the sizes of the provinces/ districts/ Tehsils from which those were selected and this was known as extrapolation.
About accuracy of these surveys, he said the margin of error of a sample survey depended upon the size of a sample and not the size of the universe, viz the margin of error of a sample of 1000 randomly selected respondents in Pakistan would be the same as that in the USA or China.
Bedil Masroor, programme producer PTV, speaking on the occasion, said that unlike the print media which had the liberty to present their point of view in a candid and free atmosphere against any institution or individual, the working of the PTV was restrained by the government. — PPI