Unlike the simple random sample and the systematic random sample, sometimes we are interested in particular strata (meaning groups) within the population (., males vs. females; houses vs. apartments, etc.). With the stratified random sample, there is an equal chance (probability) of selecting each unit from within a particular stratum (group) of the population when creating the sample. To understand more about stratified random sampling, how to create a stratified random sample, and the advantages and disadvantages of this probability sampling technique, see the article: Stratified random sampling .
Social networks (Facebook, Orkut, MySpace, Bebo, LinkedIn) are not only changing the way that many people use the Internet, but they are also presenting marketing practitioners with new challenges when trying to reach and acquire customers online. At the same time, these social networks have their own challenges in trying to acquire and retain customers when many of the traditional principles of consumer behaviour no longer apply. As social networks become more popular, a marketing dissertation in this area would be up to date and in line with current trends.
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