Find 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.

The central limit theorem has been used to calculate the figure instead of approximation. Confidence intervals for proportions show how much the results can be used in decision making about the population. A large sample makes it easy to attain a hundred percent accuracy. The samples must, however, have been taken evenly across the population if accurate results are to be obtained.

Getting the right figure is simplified if normal distribution and probability distribution are close. Indicator values of 1 for true and 0 for false make application of central limit theorem easier. The statistician must have figures that include both positive and negative figures. This means figures below and above zero.

One challenge with this approach is the fact that it is rare to find populations with negative figures. This can only happen in the case of extrapolation. The binomial approach is regarded as a better way of finding the right figures.

The figure is best given in the form of a percentage. It is more reliable working with larger figures. A lower figure indicates that a lot of assumptions were made to the extent of affecting the final answer. This becomes a challenge since the conclusions made using such information are likely to be erroneous.

The interval for the mean is obtained in a similar way. The test is aimed at offering guidance and indicators on whether the figure is correct. Too much deviation in the expected figure signals an error in the process. This method is commonly used in business and medical surveys, among other areas.

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.

Estimates give rough ideas of the expected results when computations are complete. Binomial method gives figures that are more reliable and accurate. An increased size of the sample means that accuracy levels are raised and reliable.

It is important for the data used to be uniformly collected. This works best in case it is continuous if linear sources are used. Most textbooks and classes give approximation as the best way to get the interval. There are simple formulas to use for calculations that give reliable figures as well. The important of your data will inform you on the best approach to take.

Wilson score interval, Jeffreys interval and Clopper Pearson Interval are some of the methods used in computation. Agresti Coull and Arc Sine transformation also give reliable values and are good for statistical computation. There are special cases where the data is not uniform or where assumptions need to be made.




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