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10 Feb 2011
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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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Document Summary

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. Observer"s assessment can also be biased by stereotypes. Most forms of abnormality have multiple causes. This chapter will examine the idea that stress causes depression. 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 haven"t. Null hypothesis: expectation that there is no relationship between the phenomena being studied. E. g. people who experience stress aren"t more likely to develop depression than people who don"t. 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. Independent variable: the factor that is believed to affect the dependent variable.

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