1. Running head: STATISTICAL REASONING IN PSYCHOLOGYStatistical Reasoning in Psychology Jody Marvin PSY 315 March 19, 2012 Kelly Davis, Ph.D.1

2. STATISTICAL REASONING IN PSYCHOLOGY2Statistical Reasoning in Psychology The scientific method is the approach used by scientists and psychologists systematically acquiring knowledge and understanding behavior and other phenomena of interest. Relying on contradictory, subjective, common sense to understand psychology you would have considerable difficulty establishing an acceptable theory. Psychologists meet the challenge of posing appropriate questions and properly answering them by relying on the scientific method and recently published credible primary data. Evaluating available data and research based on theory and evidence emphasizes critical thinking while referring to the results of well-designed experiments. Despite the movement discouraging psychologists from conducting significant tests, examining the role of statistics in research defends the ability to establish and continue empirical research. At present, sampling distribution is the bridge between descriptive and inferential statistics and the probability foundation of significant tests (Aron, Aron, & Coups, 2009, p. xx). Define Research and the Scientific Method Good research uses a theoretical framework, standardized procedures, is generalizable, and uses objective measurements. The scientific method is a standardized way of making observations, gathering data, and identifying questions of interest, formulating a tentative explanation (hypothesis), carrying out testing (experiments), and interpreting results. The goal is a simple scientific explanation (possibly a theory) to describe and measure behavior reproduced. Although theories are abstract statements of relationships, they are designed to describe behavior in a very broad manner (Kowalski & Westen, 2009). 3. STATISTICAL REASONING IN PSYCHOLOGY3The theory helps generate a hypothesis, or tentative belief about the relationship between two or more variables. Research continues because of inductive reasoning, including reflection on previous knowledge of facts, and general principles. Deductive reasoning leads from general to a specific cause and effect. In addition, research is cumulative and progressive. Scientists build on the work of previous researchers although an important part of any good research is the systematic inquiry aimed at the discovery of new knowledge (Kowalski & Westen, 2009). In psychology, characteristics of ideal research include identical participants in both the experimental group and control group with both groups exposed to identical testing situations (except for manipulation of the independent variable). In addition, perfect representatives within the population receive accurate and appropriate measurement of the dependent variable for what it is measuring. For example, a variable is a phenomenon that varies in individuals or changes across circumstances. Experimental manipulation of an independent variable (X) causes a change in the score of a dependent variable (Y) because of the actions from the participants or subjects (Aron, Aron, & Coups, 2009, p. 5). Random assignment to condition resolves the main issue of equivalence within participants in both groups. This results in distribution of characteristics distributed evenly across the different conditions. However, problems arise because of the Hawthorne Effect, which is the influence of attention and reaction received by a participant with prior knowledge of assignment. In addition, the placebo effect is the influence on performance from the expectation or motivation of possible benefits. At the 4. STATISTICAL REASONING IN PSYCHOLOGY4same time, a recorded instruction minimizes researchers inherent bias (Aron, Aron, & Coups, 2009, Web 1, p. 4) An experimenters dilemma is to choose whether to place more emphasis on internal validity (conclusions drawn from the results) or external validity (appropriateness and breadth). The ideal study includes identical testing conditions in an isolated location to minimize external influence by standardizing the situation while reducing interruptions. Reflecting potential limitations, results may not generalize outside the laboratory whereas complex phenomena may lack control in the lab. Validity of measure accurately samples the construct it intends to measure. Subsequently the variable predicts intended responses and behavior with reliability that produces similar scores with repeated trials (Aron, Aron, & Coups, 2009, Web 1, p. 7). Primary and Secondary Data Each research project needs information, or data, to support a hypothesis or help to understand and answer questions. Primary source data is original data or immediate data is original, such as a firsthand account of an experiment or research. The nature of the source is a clue regarding a source or data whether primary or secondary. A textbook is usually a secondary source that offers other scholars interpretations of evidence whereas a primary source provides the evidence that answers a question. Primary source data, not interpreted by anyone other than its author or creator, includes eyewitness accounts whereas secondary data is retrieved by modern scholars or commentators and possibly published subjectively (Raianski, 2003). Error within the organization that gathers data reduce reliability of secondary data. The reliability of data is a function of the organization that gathers, organizes, records, 5. STATISTICAL REASONING IN PSYCHOLOGY5and publishes secondary data. Concurrently, a definite time lag exists between the time the primary data transpires and the time it is made available. Clerical error, error due to change in collection procedure, and error due to corrected data alter the reliability of secondary data. Along with credentials and credibility of either a primary data resource or a secondary data source, always check the newest versions of the data set (Raianski, 2003). The Role of Statistics Statistics is a discipline concerned with the method of pursuing the truth, evaluating the reliability of data, thinking about outcomes, underlying principles, and logic. Organization, analysis, and interpretation of a group of numbers are the branch of mathematics that Statistics focus. The goal is to solve a problem with analysis of numerical or nominal data. You can enter data related, and see what the results are if you change the data. You can create charts and graphs, calculate, and present differences and similarities to illustrate the scientific data graphically and over time. In contrast, you can scientifically show the parts of the data fitting together. Statistics use its own set of tools such as tdistribution, and pvalue the probability associated with the truth of a hypothesis, (Maillardet, 2009, para. 12). Achieved through random assignment to condition and Laws of Probability, basic logic behind analysis infers the independent variable causes the change. Categorical variables (nominal) involve groups or classifications whereas continuous variables (numerical) involve an infinite amount of values such as age, height, or blood alcohol levels. Statistical significance is a mathematical measure of the validity of an experiment showing the results are either within a narrow margin of the control (base 6. STATISTICAL REASONING IN PSYCHOLOGY6values) or are all over the chart. Because one definite conclusion is impossible from the data, recording a possible error, again, emphasizes studies involving humans are never 100% (Aron, Aron, & Coups, 2009, Web 1, p. 6). 7. STATISTICAL REASONING IN PSYCHOLOGY7References Aron, A., Aron, N., & Coups, E. (2009).Statistics for Psychology (5th Ed.). Upper Saddle River, NJ: Pearson, Prentice Hall, Inc. Kowalski, R., & Westen, D. (2009). Psychology (6th Ed.).Hoboken, NJ: Wiley & Sons, Inc. Raianski, J. (2003). Primary and secondary data.Appraisal Journal, 71(1), 43,13. Retrieved from http://www.appraisal