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Monday, April 21, 2014

Finding The Confidence Intervals For Proportions

By Essie Osborn


A confidence interval in statistics is termed as range within which an answer is expected. It is used to indicate the estimate the reliability of a set of data. It indicates possible values if the same experiment were to be repeated within the population. The ease with which the next experiment will deliver similar results increases reliability.

One of the approaches used is the central limit theorem. It gives a value that indicates the distribution of the aspect being interrogated by the research. Larger figures increase the accuracy of figures obtained when computing confidence intervals for proportions. It is important to have even distribution during sampling to improve on the accuracy of the results.

Probability and normal distribution must be close to ensure that the figure obtained is correct. A researcher who uses the central limit had better be working with 1 as a true indicator and 0 as false. Statistics with positive and negative figures are easier to work with. The figures should be below and above zero.

Finding a research with negative figures is sometimes very difficult. This has made the use of the theorem a bit challenging. The method is, however, effective when working with extrapolations. Use of binomial approach will work with many cases.

The confidence interval is given as a percentage. Using a larger population sample makes it possible to obtain an accurate figure. A lesser figure is likely to indicate that too many assumptions were made such that the results cannot be accurate. Conclusions based on this figure are likely to be erroneous.

The interval for a mean indicates a value within which the real figure must lie. It tests the reliability of an estimate. If the value lies outside the bounds set, the research is regarded as doubtful. Such an interval is used in different fields including business and medicine.

Wide intervals indicate that there is need to collect more data. It implies that the figures given in this case are not totally reliable or representative of expected results. A definite conclusion cannot be made from a data whose interval is quite wide. Using such information is likely to lead to an erroneous conclusion.

An estimate is a way of giving a rough idea to indicate expected results upon completion. The binomial method is more accurate and gives more reliable data. Increasing the size of your sample assists in raising the level of accuracy.

Uniformity in correction of data increases the level of accuracy. Data that is arranged in a linear format is better to use when making conclusions. The approximation method is common in statistic classes and text books. The formula to use in each case depends on the data available. Working with smaller figures and more valuables requires a different formula compared to fewer figures.

The methods used range from Clopper Pearson Interval, Jeffreys interval and Wilson score interval approaches. Others are Arc Sine transformation and Agresti Coull methods that are known for the reliability of their values. The discrepancies in the figures obtained largely depend on assumptions and accuracy of data collected.




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