2010 Census Results - United States
The new apportionment figures were revealed by the Census Bureau, which fulfilled its once-in-a-decade mandate to survey residents in order to gauge population migration across the country.
As of April 1, 2010, the Census Bureau estimated the U.S. population at 308,745,538 million people — an increase of 9.7 percent from the 2000 Census.
Sample survey about smoking
Eighty-one per cent of Maltese smokers want to kick the habit, according to a survey by the European Commission's Ex-Smokers Are Unstoppable campaign. The survey, carried out on a sample of 200 people, also showed that almost 52 per cent of Maltese believe that smoking is one of the hardest habits to break. More than four in 10 of those questioned felt that smoking was getting in the way of doing an activity.
Sample Survey & Methods
Till now, we learned about exploratory analysis of data whereas in this topic, we discuss various methods for collecting the data. There are four main methods of data collection: Census, Sample survey, Experiment and Observational study.
Census: A census is the process of collecting the data (or) information from all the members in a population. It is also known as complete enumeration of population [i.e., complete count of population]. For example, if we are studying the weights of students of a school, 'all' the students of the school constitute the population.
The information which is collected by census method is accurate and authentic but the authenticity of data is a function of sincerity of enumerators. This method is convenient for small size populations because associated cost and time consumed for collecting the data is less.
If the size of population is large then time consumed for collecting the data is more and we require large number of qualified enumerators for collecting the data. Hence, in case of large populations, data may become outdated by the time it is collected and analyzed.
Sample survey: It is the process of collecting (or) obtaining the information about the whole population by studying a part of it, that is, a sample. The main goal of this is to collect the information without disturbing (or) changing the population.
In this method, data collection is faster and cost is lower because we are considering only a part of a population [i.e., sample]. The information which is obtained from this method is used to make the inferences about the population parameters.
The main problem which occurs in sample survey is bias [which quickly invalidates a sample and makes useful information impossible to obtain]. A sample is biased if in some critical way it does not represent the population. The main technique to avoid bias is to incorporate randomness into the selection process. This randomization protects us from effects and influences.