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Chapter 3

CH3 Textbook Notes


Department
Psychology
Course Code
PSY240H1
Professor
S.Cassin
Chapter
3

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CHAPTER 3 THE RESEARCH ENDEAVOUR
- challenges in studying psychopathology
- populations of interest can be difficult to convince to participate in research
- abnormal behaviours and feelings are difficult to measure accurately
- researchers often rely on self-report of their internal states and experiences
- observers assessment can also be biased by stereotypes
- most forms of abnormality have multiple causes
- this chapter will examine the idea that stress causes depression
The Scientific Method
Defining the Problem and Stating a Hypothesis
- hypothesis: a testable statement of what we predict will happen in the study
- e.g. people who have recently experienced stress are more likely to be depressed than
people who havent
- null hypothesis: expectation that there is no relationship between the phenomena being
studied
- e.g. people who experience stress arent more likely to develop depression than people
who dont
Choosing and Implementing a Research Method
- variable: a factor or characteristic that can vary within an individual or between individuals
- e.g. weight, mood, neurotransmitter level, height, sex, ethnicity
- dependent variable: the factor being predicted in a study
- e.g. depression
- independent variable: the factor that is believed to affect the dependent variable
- e.g. stress
- depression: a syndrome or collection of the following symptoms: sadness, loss of interest in
ones usual activities, weight loss/gain, changes in sleep, agitation/slowing down, fatigue and
loss of energy, feelings of worthlessness/excessive guilt, concentration
problems/indecisiveness, suicidal thoughts
- stress: peoples emotions and behaviours in response to a stressor (an uncontrollable and
unpredictable event that challenges the limits of peoples abilities to cope)
- operationalization: the way a researcher measures or manipulates the variables in a study
- if we define depression as symptoms meeting criteria for a depressive disorder, we will
operationalize depression as diagnoses
- if we define depression as symptoms along a range of severity, we will operationalize
depression as scores on a depression questionnaire
- in operationalizing stress, must decide whether to focus on stressful events or on
peoples stress reactions to these events
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Case Studies
- detailed histories of individuals who suffered a form of psychological disorder
- used to understand the experiences of individuals and make general inferences about the
sources of psychopathology
- e.g. interview an individual to discover links between periods of depression and stressful
events in their life, interview close friends and family and based on the information, create a
detailed description of the causes of their depressive episodes emphasizing the role of stressful
events in these episodes
- useful in studying rare disorders
- invaluable in helping generate new ideas and provide tentative support for those ideas
- common use today: drug treatment research report unusual reactions patients have to certain
drugs
Evaluating Case Studies
- generalizability: ability to apply what has been learned to other individuals or groups
- conclusions drawn from a case study may not apply to many other individuals
- lack of objectivity, two case studies of the same person may come to very different conclusions
about the motivations and key events in that persons life
- difficulties in replication
Correlational Studies
- examines relationship between an IV and a DV without manipulating either
- most common in abnormal psychology is a study of two or more continuous variables:
measured along a continuum
- e.g. severity of depression (0-100) and number of recent stressors (0-20)
- comparison study: studies relationship between peoples membership in a particular group and
their scores on some other variable
- e.g. look at the relationship between depression and whether or not people have
experienced a loss of a loved one, groups are bereaved and non-bereaved
- at least one variable isnt a continuous variable
- studies can either be cross-sectional: observe people at only one point in time, or longitudinal:
observe people on two more occasions over time
- longitudinal studies can show that the IV precedes and predicts changes in the DV over
time
Measuring the Relationships Between Variables
Correlation Coefficient
- a statistic used to represent the relationship between variables, usually denoted with the
symbol r, falls between -1 and +1
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Statistical Significance
- an index of how likely that result occurs by chance
- usually see the result was statistically significant a p<0.05 meaning that the probability is less
than 5 in 100 that the result occurred only by chance
- whether a correlation coefficient will be statistically significant at the p<0.05 is determined by
its magnitude and the size of the sample
- larger correlation and larger sample sizes increase likelihood of achieving statistical
significance
Correlation versus Causation
- even if an IV and a DV are highly correlated, it doesnt mean that the IV causes the DV
- does mean there is a relationship between the two
- could be the depression causes stress or a third variable cause both stress and
depression
- third variable problem: the possibility that variables not measured are the real cause of
the relationship between the variables
Selecting a Sample
- sample: a group of people taken from the population that we want to study
Representativeness
- a representative sample highly similar to the population of interest in terms of sex, ethnicity,
age, and other important variables
- important to the generalization of the study
Selection of a Comparison Group
- comparing the experiences of one group with those of another
- e.g. bereaved and non-bereaved people
- in selecting the comparison group, the non-bereaved group should match the bereaved group
on variables (other than stress) that might influences levels of depression e.g. sex, age
Evaluating Correlational Studies
- focus on situations occurring in the real world rather than in a lab
- good external validity: the extent to which a study’s result can be generalized to the
phenomena in real life
- cannot differentiate what is a cause and what is a consequence
- potential for bad timing but longitudinal studies are time-consuming and expensive to run
- all can have the third variable problem
Epidemiological Studies
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