# Author Archives: Zhuldyz Ashikbayeva

## Confidence Interval for Two Independent Proportions

Confidence interval for two independent proportions gives an estimated range of values, which is likely to include the difference between the two true population proportions for two categorical variables. For example, medical researchers may want to compare the proportions of men and women who suffered from heart attacks. The procedure for obtaining such an interval […]

## Pearson Correlation Coefficient (r)

The Pearson Correlation Coefficient (or the Pearson Product Moment Correlation) is the measure of the strength of the linear association between two quantitative variables. The formula is: , where and are the standard scores for x and y that show how many standard deviations x and y are from the mean and n is the […]

## Pie Charts

A pie chart is a circular graphical display for a single categorical variable. The graph is divided into segments, each representing a particular category. Each segment is the same proportion of a circle as the category is of the total data set. The percentages in the pie chart must add up to 100%. Pie charts […]