Statistical Methods In Statistics

Measures of location After the collection and presentation of data the next step involved in statistical analysis is to understand and apply the mathematical techniques for the interpretation of data. Application of statistical method is easy helps to remove doubts . We may first learn method of analysing quantitative data in which characteristics and frequency are both variable such as calculation of averages, percentiles, standard deviation, standard error. These are used frequently in anatomy & physiology to define limits of normality. To define what is normal in case of height, weight, WBC count, haemoglobin percentage etc. Normal is not the central value but it is the range of variation on either side of the average or mean within accepted

Percentiles are calculated as a means of dividing a distribution of values into 2 or more groups. They are used to determine where to draw the line between observed values within the distribution. For example: if a teacher wishes to determine the exam score that divides his class in half, with 50% scoring above and 50% scoring below, he determines the point that marks the 50 percentile. In statistics, there are percentile scales which have special names for various percentiles. Deciles are percentiles which divide a distribution into ten equal sections. There are nine deciles in each distribution of values which correspond to the 10th, 20th, 30th,...90th percentiles. Quartiles are points in a distribution which divide that distribution into quarters. The first quartile (Q1) is the 25th percentile. The second quartile (Q2) is the 50th percentile or the median. The 75th percentile is the third quartile (Q3). A percentile rank is used to determine where a particular score or value fits within a broader distribution. For example: A student receives a score of 75 out of 100 on an exam and wishes to determine how her score compares to the rest of the class. She calculates a percentile rank for a score of 75 based on the reported scores of the entire class. Her percentile rank in this example. would be 80, meaning that 80 percent of scores on the exam were at or below 75. Calculating the percentile rank of a score of

This is also called as measures of central location or summary statistics. Mean is often known measure of central tendency, along with mean there are median and mode which are also used. The mean, median and mode are all valid measures of central tendency, but are useful in different conditions. Some measures of central tendency become more appropriate to use than others. Now we are going to see what is mean, mode and median, and learn how to calculate them and where they are most appropriately used.

Mean or Arithmetic Mean -

Most popular and well known measure of central tendency. It can be used with both discrete and continuous data. Its most often use is with continuous data. The mean is value obtain from the sum of all the values in the data set divided by the total number of values in the data set. So, if we have n values in a data set with values x1, x2, ..., xn, the sample mean, usually denoted by (pronounced as "x bar"),