PSY 221E PSYCHOLOGICAL STATISTICS REVIEWER MODULE 1: INTRODUCTION TO PSYCHOLOGICAL STATISTICS

PSYCHOLOGICAL STATISTICS REVIEWER MODULE 1: INTRODUCTION TO PSYCHOLOGICAL STATISTICS STATISTICS  Statistics refers to a set of mathematical procedures for organizing, summarizing, and interpreting information.  ...

PSYCHOLOGICAL STATISTICS REVIEWER MODULE 1: INTRODUCTION TO PSYCHOLOGICAL STATISTICS STATISTICS  Statistics refers to a set of mathematical procedures for organizing, summarizing, and interpreting information.  Statistics condense large quantities of information into a few simple figures. IMPORTANCE AND USE OF STATISTICS IN PSYCHOLOGY  Research – statistical procedures provide researchers with objective and systematic methods for describing and interpreting their research results.  Statistics serve two general purposes: 1. Statistics are used to organize and summarize the information so that the researcher can see what happened in the research study and can communicate the results to others. 2. Statistics help the researcher to answer the questions that initiated the research by determining exactly what general conclusions are justified based on the specific results that were obtained.  Test/Scale Development – to create and develop psychological measures that are valid and reliable.  Decision-making – “statistics” refers to range of techniques and procedures for analyzing, interpreting, displaying, and making decisions based on data.  Useful in different settings where psychology is applied. It adds credibility to arguments.  Learning statistics can help in making you an intelligent consumer of statistical claims. IMPORTANT TERMS  Variable - a characteristic or condition that changes or has different values for different individuals. Example: level of intrinsic motivation, type of antidepressant, age, weight, height, gender, or personality  A variable is a set of values that can differ for different people. For example, we often measure variables such as age and gender. The term variable is synonymous with quality, attribute, trait, or property. Constructs are also variables.  Variable is anything assigned to people that can potentially take on more than just a single constant value.  A variable is a characteristic or condition that changes or has different values for different individuals.  Variables can be environmental conditions that change, such as temperature, time of day, or the size of the room in which the research is being conducted. To demonstrate changes in variables, it is necessary to make measurements of the variables being examined. The measurement obtained for each individual is called a datum or, more commonly, a score or raw score. The complete set of scores is called the data set or simply the data.  Participant variables - characteristics such as age, gender, and intelligence that vary from one individual to another. Whenever an experiment compares different groups of participants researchers must ensure that participant variables do not differ from one group to another.  Environmental variables - characteristics of the environment such as lighting, time of day, and weather conditions. A researcher must ensure that the individuals in treatment are tested in the same environment as the individuals in treatment B.  Independent variable - variable that is manipulated by the researcher. The independent variable consists of the antecedent conditions that were manipulated prior to observing the dependent variable.  Dependent variable - variable that is observed to assess the effect of the treatment. The purpose of a control condition is to provide a baseline for comparison with the experimental condition.  Discrete variables - refer to variables that can be obtained through counting like the number of deaths, births, students and marriages; whole numbers.  Continuous variables - can never be exact no matter what we do in getting the measurement (e.g. temperature, weight, height); decimal numbers.