Population in the news

As stated by Gould W.T.S in Population and Development, “the urgency of the need to understand the relationships between population and population change and local and global development at the beginning of the twenty-first century is highlighted by the fact that three of the eight Millennium Development Goals (MDGs) of the United Nations (UN), to be achieved by 2015, explicitly deal with a major population concern.”( Gould, 2009,p1).

One of the ways to deal with some of the problems arising from population is to determine the population mean.The population mean is the center of a number of values of a numerical variable based on the collection of individuals under consideration. It’s a figure representing the center of a particular population distribution and can therefore be considered as a population parameter.In estimating the mean one should account for errors encountered during the sampling of a particular population this is the marginal error (Jean, 2009).

The population mean is given by

where N is the population size and is the sum of the sample values.

A Margin of error is a boundary that we can confidently place on the difference between an estimate of the population and its true value (William, et al.2009)

The Margin of Error for a sample of size n is given by:

1/√n

The measure of how we can give the margin of error is known as Confidence level (Long Island Newsday, 2010). The confidence interval is the interval of numbers containing the most probable values for our population parameterand is given by:

The following sample article, about a research done on the New York teachers’ performances rankings in the year 2009-2010 where approximately 12000 teachers were sampled, is obtained from the Long Island Newsday.

The above article was a result of research done from 2007 to 2010 by the New York City in an attempt to measure how teachers affected student test scores, using a specific formula.Themargin of error indicates the probability of where the score could fall. Generally as the sample size increases the margin of error decreases and as the confidence level increases the margin of error increases. Basically the larger the confidences level the wider margin of error (The wall street journal 2010).

Reference.

Gould W.T.S (2009) Population and Development. Population is a development issue (pp1).

Long Island Newsday. (2010).2009-2010 New York City Teacher Data Reports. Retrieved from http://data.newsday.com/long- island/database/?pid=412&currentRecord=501

Jean H.S (2009) Basic Statistics for Trainers. Margin of error. (pp8)

The wall street journal (2010). Wide variation spark skepticism-WSJ.com. Retrieved from online.wsj.com/article/SB10001424052970203918304577243690477706160.html

William M, Robert J.B, & Larbara M.B (2009) Introduction to Probability and Statistics. Large sample estimation (pp 314-316).