UNIT 2

• Psychologists and other scientists share three sets of interrelated goals: measurement and description, understanding and prediction and application and control
• hypothesis is a tentative statement about the relationship between two or more variables
• variables are any measurable conditions, events, characteristic, or behaviours that are controlled or observed in a study
• theory is a system of interrelated ideas used to explain a set of observations
• what are the five steps in a scientific investigation?

  1. formulate a hypothesis
  2. design a study
  3. collect data
  4. analyze the data
  5. report the findings
• operational definition describes the actions or operations that will be used to measure or control a variable
• participants are the persons or animals whose behaviour is systematically observed in a study
• a journal is a periodical that publishes technical and scholarly material, usually in a narrowly defined area on inquiry
• Research methods consist of various approaches to the observation, measurement, manipulation, and control of variables in empirical studies
• independent variable is a condition or event that an experimenter varies in order to see its impact on another variable
• dependent variable is the variable that is thought to be affected by manipulation of the independent variable
• experimental group consist of the subjects who receive some special treatment in regard to the independent variable
• the control group consists of similar subjects who do not receive the special treatment given to the experimental group
• extraneous variable are any variables other than the independent variable that seem likely to influence the dependent variable in a specific study
• a cofounding of variables occurs when two variables are linked in a way that makes it difficult to sort out their specific effects
• Random assignment of participants occurs when all participants have an equal chance of being assigned to any group or condition in the study
• Field experiments are research studies that use settings that are very much like real-life situations.
• naturalistic observation a researcher engages in careful observation of behaviour without intervening directly with the subjects
• reactivity occurs when a participant's behaviour is altered by the presence of the observer
• Case study is an in-depth investigation of an individual participant or group of participants
• Survey is when researchers use questionnaires or interviews to gather information about specific aspects of participants behaviour
• descriptive research broadens the scope of phenomena that psychologist are able to study
• Descriptive/correlational research cannot demonstrate conclusively that correlated variables are casually related
• statistics is the use of math to organize, summarize, and interpret numerical data
• descriptive statistics are ise to organize and summarize data
• Median is the score that falls exactly in the centre of distribution scores
• the mean is the average of the scores
• mode is the most frequent score in a distribution
• variability refers to how much the scores in a data set vary from each other and from the mean
• the standard deviation is an index of the amount of variability in a set of data
• normal distribution is a symmetrical, bell-shaped curve that represents the pattern in which many humans characteristics are dispersed in the population
• a percentile score indicated the percentage of people who score at or below a particular score
• correlation exists when two variables are related to each other
• The correlation coefficient is a numerical index of the degree of relationship between two variables. A correlation coefficient indicates 1. the direction (+ or -) of the relationship and 2. how strongly the two variables are related
• positive correlation indicates that two variables co-vary in the same direction; High X score, Hight Y scores
• negative correlation indicated that two variables co-vary in the opposite direction; inverse relationship- X score low, Y score high
• The strength of the correlation is the size of the coefficient; the coefficient can vary between 0 and +1.00 (positive) or 0 and -1.00 (negative)
• A coefficient near 0 indicated no relationship between the variables; high or low scores on X show no consistent relation- to high or low scores on Y. A coefficient of +1.00 or -1.00 indicates a perfect, one-to-one correspondence between the two variables
• Correlation and Prediction: As a correlation increases in strength (gets closer to either − 1.00 or +1.00), the ability to predict one variable based on knowledge of the other variable increases.
• correlation and causation: correlation does not imply causation, and causation does not imply correlation