Descriptive and Inferential Statistics

Statistics are widely used when conducting research, and the field of psychology is no exception. Statistics are used in psychology for all research and has made categorizing disorders possible. Statistics have helped accomplish a number of feats and they are important for a variety of reasons. The purpose of this paper is to describe the function of statistics, define descriptive and inferential statistics, and provide an example of the relationship between the two. 

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Wikipedia defines statistics as the “…mathematical science involving the collection, interpretation, analysis, and presentation of data” (Statistics, 2009, p. 1). Statistics has come to play an important role in almost every field of life and human activity. It is often used to make predictions based on data and it is widely applicable in various social and natural sciences such as psychology and education. In experimental psychology, whenever a problem has to be studied and based on a sample statistics is used. It is used in business in that it provides a quantitative basis for making decisions in all matters. Statistical methods are also used in analyzing experimental data and drawing conclusions. There is hardly any field where statistical data and methods are not used for one purpose or the other. According to Webster’s Online Dictionary statistics is a branch of applied mathematics which includes planning, summarizing, and interpreting of uncertain observations (Definition, 2009). As is apparent, statistics holds a central position in every field of science and its importance is increasing every day. 

Descriptive and inferential statistics are the two main parts of the statistical system. To begin to describe the two someone would have to understand their respective meaning. Aron, Aron, and Elliot (2006) frame descriptive statistics by explaining that “…Psychologists use descriptive statistics to summarize and make understandable—to describe—a group of numbers from a research study” (p. 2). Basically, descriptive statistics is a way for psychologists to make their studies understandable and make sense. Any numbers in a row can mean anything but once that information is described and broken down other people have the chance to make sense of the findings to be studied and have a meaning. Without descriptive statistics, the research and meaning might be lost when trying to be understood. Then, on the other hand, there is inferential statistics which is also outlined by Aron, Aron, and Elliot (2006) by explaining that, “…Psychologists use inferential statistics to draw conclusions and make inferences that are based on the numbers from a research study but go beyond these numbers” (p. 1). What inferential statistics means goes beyond the numbers. It is the ending of the research and the numbers, it is the reason why statistics was used and explain what the research lead the psychologists to understand. In conclusion, descriptive and inferential statistics is the reason why statistics is crucial to psychology. It is what allows the researchers to make sense of their data and be able to conclude it in a study, without the two statistics would not flow properly in psychology. 

This graph is a classic example of the normal curve, a theoretical standard of statistical calculation. The graph is theoretical because it is rarely duplicated exactly in everyday life; however, the curve itself represents a benchmark for the graphical understanding of statistical data (Aron, Aron, & Coups, 2006). In the realm of descriptive statistics, the normal curve exemplifies an optimum model of central tendency; namely, that the mean, mode, and median all occupy the same position on the distribution. The normal curve also epitomizes the ideal unimodal, kurtosis neutral, symmetrical distribution. In fact, the basis for the idea of kurtosis rests on the deviation of the tails of the distribution from the standard normal curve.

Furthermore, the formula for standard deviation, the typical amount that values differ from the mean, is; and can be used both as a descriptive instrument and an inferential device. The standard deviation of a distribution of number can be used to describe the variation of the scores from the mean, but can further be used to infer future probabilities of distributions. Going back to the normal curve, it has been estimated that 34% of scores fall within the mean and one standard deviation and that 14% of scores fall between one and two deviations from the mean. While taking these known quantifications into account it is possible to deduce a score given the percentage of the distribution or to conversely deduce the percentage given the score. In this way, the normal curve can be used as a benchmark for distribution description as well as an inferential instrument for the prediction and quantification of scores.   

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Statistics are needed for all sorts of research and are essential to the field of psychology. It allows researchers to gather and categorize their data as well as be able to state their claims with easy, readable information to back it up. Descriptive and inferential statistics make this possible for psychologists. Descriptive and inferential statistics work together to obtain reliable data that researchers can use for many different studies, thereby producing usable information. Without statistics, this research would not be possible. Statistics really moved the field of psychology. Looking at all that statistics is involved with it can be a bit overwhelming. Statistical research made it possible for psychology to move into the 20th century and beyond. 


Aron, A., Aron, E., & Coups, E. (2006). Statistics for psychology (4th ed.). Upper Saddle River, NJ: Pearson/Allyn Bacon.

Definition: Statistics. (2009). In Webster’s Online Dictionary. Retrieved March 2, 2009, from

Statistics. (2009). In Wikipedia, The Free Encyclopedia. Retrieved March 2, 2009, from

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