# Statistical treatment in thesis writing

To find the quartiles, use the same procedure as for the median, but take the quarter- and three-quarter-point instead of the mid-point.

## Percentage analysis statistical tool

Measures of Spread: Range, Variance and Standard Deviation Researchers often want to look at the spread of the data, that is, how widely the data are spread across the whole possible measurement scale. This is important because it shows you straight away whether your data are grouped together, spread about, tending towards high or low values, or clustered around a central point. Excel can analyse descriptive statistics at a simple level and when used effectively, can be very useful in the exploratory analysis of data, cross tabulations pivot charts , viewing data in graphs to detect errors, unusual values, trends and patterns and summarising data with means and standard deviations. To understand whether actual change has taken place, this requires the confidence interval of the difference between the two means to be tested see further reading for a link to a web tool for measuring the confidence interval between two means. It is not hard to draw a histogram or a line graph by hand, as you may remember from school, but spreadsheets will draw one quickly and easily once you have input the data into a table, saving you any trouble. Pie charts are best used when you are interested in the relative size of each group, and what proportion of the total fits into each category, as they illustrate very clearly which groups are bigger. They will even walk you through the process. The sample used in survey 2 also needs to be independent from the sample used in survey 1. When most people say average, they are talking about the mean. Formal Statistical Packages. See our page: Charts and Graphs for more information on different types of graphs and charts. It cannot be used for further statistical analysis. To find the quartiles, use the same procedure as for the median, but take the quarter- and three-quarter-point instead of the mid-point. You should choose a non-parametric test if the population clearly does not follow a normal distribution. They are calculated by: calculating the difference of each value from the mean; squaring each one to eliminate any difference between those above and below the mean ; summing the squared differences; dividing by the number of items minus one.

Choosing the right test Choosing between these two families of tests can be difficult. Measures of Location: Averages The average gives you information about the size of the effect of whatever you are testing, in other words, whether it is large or small.

This page provides a brief summary of some of the most common techniques for summarising your data, and explains when you would use each one. Analysis of variance ANOVA — This is used to test hypotheses about differences between two or more means as in the t-test, however when there are more than two means, analysis of variance can be used to test differences for significance without increasing the error rate Type I.

This is the mid-point of all the data.

## Statistical tools for data analysis pdf

Measures of Spread: Range, Variance and Standard Deviation Researchers often want to look at the spread of the data, that is, how widely the data are spread across the whole possible measurement scale. Further, these packages can produce charts, graphs and tables from the results of the analysis. Kruskal-Wallis test — A non-parametric method for testing equality of population medians among groups, using a one-way analysis of variance by ranks. The sample used in survey 2 also needs to be independent from the sample used in survey 1. The mode is the most common value in a data set. How should it be analysed? This means that the data has less of a tendency to produce unusually extreme values, compared to some other distributions. This is important because it shows you straight away whether your data are grouped together, spread about, tending towards high or low values, or clustered around a central point. This page provides a brief summary of some of the most common techniques for summarising your data, and explains when you would use each one. See our page: Charts and Graphs for more information on different types of graphs and charts. To select the right test, you need to ask yourself two questions: What kind of data have you collected? They will even walk you through the process. Regression linear and non linear — A technique used for the modelling and analysis of numerical data. More Advanced Analysis Once you have calculated some basic values of location, such as mean or median, spread, such as range and variance, and established the level of skew, you can move to more advanced statistical analysis, and start to look for patterns in the data.

This confidence interval would fall to 0. The same data as in the bar chart are displayed in a line graph below.

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