PSYC10004 Lecture Notes - Lecture 2: Categorical Variable, Descriptive Statistics, Statistical Inference
2. How Human Development is Studied
The Scientific Method
The Scientific Method: a process of generating ideas and testing them by making observations.
• preliiary oseratios proide ideas for:
theory: a set of concepts and propositions to describe and explain certain phenomena
theories generate hypothesis → research studies test hypothesis
Hypothesis: is a tentative belief about the relationship between two or more variables. It predicts the findings
that should be observed if the theory is correct
Variable: any phenomenon that can differ, or vary, from one situation to another or from one person to
another
Continuous variable: a variable that can be placed on a continuum (degree of optimism, intelligence, etc.)
Categorical variable: comprised of groupings or categories (gender, species, etc.)
Standardised procedures: participants in a study are exposed to as similar procedures as possible.
Quantitative research: typically involves using experiments or surveys to gather data that can be statistically
analysed to test particular hypotheses.
• Normally based on large sample sizes representative of the population
• Can usually be replicated or repeated, giving it high reliability
• Analysis of results is more objective than qualitative research, often using standardised techniques
• Takes a deductive and objective approach
• Conclusions about predetermined hypothesis are drawn from the results of scientifically controlled
testing
• Interviews, observations and case studies
• More inductive and subjective than quantitative research
• Often researcher does not begin with predetermined hypothesis but develops them based on outcome
of research process
• Rather than using statistical analyses to confirm hypothesis objectively, the researcher must make a
subjective judgement about what the data means.
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Generalisability: the applicability of the findings to the entire population of interest
Sampling bias: occurs when the sample is not representative of the population as a whole
For a study to be generalizable, its procedures must be sound or valid and must have both internal and
external validity.
Internal validity: the validity of the design itself. If a study has flaws such as unrepresentative sample or non-
standardised aspects of the design that affect the way participants respond, its internal validity is
jeopardised
External validity: applicability to situations external to the laboratory
Measure: a concrete way of assessing a variable, a way of bringing an often abstract concept down to earth
A measure is reliable if it produces consistent results
A easure is alid if it aurately assesses or saples the ostrut it is intended to measure
Random sample: a sample selected from the general population in a relatively arbitrary way that does not
introduce any systematic bias and where every member of the population has an equal chance of being
selected for the sample
Stratified random sample: specifies the percentage of people to be drawn from each population category and
then randomly selects participants from within each category
Theories generate hypothesis which are tested through observation of behaviour
A good theory must be:
• Internally consistent: its different parts and propositions should hang together and not generate
contradictory hypotheses
• Falsifiable: can be proved wrong
• Supported by data: predictions can be confirmed by research results
Data collection:
• fid appropriate ay to easure hat ere iterested i
• vary on age group and aspects of development being studied
Major methods:
• Verbal Reports
• Behavioural Observations
• Physiological Measurements
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Verbal Reports: interviews, questionnaires/surveys, personality scales, ability/achievement tests
Pros:
• questions asked in same order, easy to compare
Cons:
• cannot be used on infants and young children
• different ages understand questions differently
• participants represent themselves in a positive or socially desirable light
Naturalistic observation: the in-depth observation of a phenomenon in its natural setting
Pros:
• findings are clearly applicable outside laboratory
Cons:
• difficult to generalise
• researcher bias, can be minimised by observing several groups of participants or by videotaping
interactions
• primarily describes behaviours rather than explain why
Survey research: asking questions of a large sample of people usually about attitudes or behaviours
Most frequently used tools: interviews and questionnaires
Behavioural Observations: observing people in their everyday surroundings
Pros:
• infants and young children lacking verbal skills can be studied
Cons:
• some behaviours occur infrequently and unexpectedly
• hard to isolate cause of behaviour as many events happen at the same time
• presence of observer may affect behaviour
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Document Summary
Hypothesis: is a tentative belief about the relationship between two or more variables. It predicts the findings that should be observed if the theory is correct. Variable: any phenomenon that can differ, or vary, from one situation to another or from one person to another. Continuous variable: a variable that can be placed on a continuum (degree of optimism, intelligence, etc. ) Categorical variable: comprised of groupings or categories (gender, species, etc. ) Standardised procedures: participants in a study are exposed to as similar procedures as possible. Generalisability: the applicability of the findings to the entire population of interest. Sampling bias: occurs when the sample is not representative of the population as a whole. For a study to be generalizable, its procedures must be sound or valid and must have both internal and external validity. Internal validity: the validity of the design itself.
