Irfan Ahmed, PhD

Errors in Statistical Data In sample surveys there are two types of error that can occur: sampling error which arises as only a part of the population is used to represent the whole population and; non-sampling error which can occur at any stage of a sample survey. It is important to be aware of these errors so that they can be minimized. Sampling error Sampling error is the error we make in selecting samples that are not representative of the population. Since it is practically impossible for a smaller segment of a population to be exactly representative of the population, some degree of sampling error will be present whenever we select a sample. It is important to consider sampling error when publishing survey results as it gives an indication of the accuracy of the estimate and therefore reflects the importance that can be placed on interpretations. If sampling principles are carefully applied within the   constraints of available resources, sampling error can be accurately ...

“You don’t have to eat the whole ox to know that the meat is tough.” Samuel Johnson Data collecting instruments The choice of data collection instrument is crucial to the success of the survey. When determining an appropriate data collection method, many factors need to be taken into account, including complexity or sensitivity of the topic, response rate required, time or money available for the survey and the population that is to be targeted. Some of the most common data collection methods are described in the following sections. 1.          Interviewer enumerated surveys Interviewer enumerated surveys involve a trained interviewer going to the potential respondent, asking the questions and recording the responses. The advantages of using this methodology are: _ provides better data quality _ special questioning techniques can be used _ greater rapport established with the respondent _ allows more complex issues to be included _ produces ...