# media

Topics: Sampling, Sample size, Sampling error Pages: 2 (601 words) Published: November 4, 2014

Designing a research project takes time, skill and knowledge. With Qualtrics survey software, we make the survey creation process easier, but still you may feel overwhelmed with the scope of your research project. Here are 5 common errors in the research process.

1. Population Specification
This type of error occurs when the researcher selects an inappropriate population or universe from which to obtain data. Example: Packaged goods manufacturers often conduct surveys of housewives, because they are easier to contact, and it is assumed they decide what is to be purchased and also do the actual purchasing. In this situation there often is population specification error. The husband may purchase a significant share of the packaged goods, and have significant direct and indirect influence over what is bought. For this reason, excluding husbands from samples may yield results targeted to the wrong audience. 2. Sampling

Sampling error occurs when a probability sampling method is used to select a sample, but the resulting sample is not representative of the population concern. Unfortunately, some element of sampling error is unavoidable. This is accounted for in confidence intervals, assuming a probability sampling method is used. Example: Suppose that we collected a random sample of 500 people from the general U.S. adult population to gauge their entertainment preferences. Then, upon analysis, found it to be composed of 70% females. This sample would not be representative of the general adult population and would influence the data. The entertainment preferences of females would hold more weight, preventing accurate extrapolation to the US general adult population. Sampling error is affected by the homogeneity of the population being studied and sampled from and by the size of the sample. 3. Selection

Selection error is the sampling error for a sample selected by a nonprobability method. Example: Interviewers conducting a mall intercept study have a natural...