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PS101 Lecture Notes - Statistical Inference, Statistical Hypothesis Testing, Central Tendency

Course Code
Lawrence Murphy

of 4
midterm-october 17th
50 mc choice
arrive at 6:20 and write for 1 hour
Chapter 2
Scientific approach
a search for laws
theory-proven hypothesis-i.e theory of gravity
figure 2.1
basic assumption:events are goverend by some lawful order
measurement and description
understanding and prediction
Application and control
operational definitions used to clarify precisely what is meant by each variable
understanding and visually simplfying certain idea's (i.e emotions, visually expressing
participants or subjects are the ogranims whose behaviour is systemically observed in a study
Data collection techniques allow for empirical observation and measurement
Statistics are used to analyze daya and decide whether hypotheses were supported
cannot be used to prove anything
finding are shared through reports at a scientific meeting and in scientific journal-periodicals
that publish technical and scholary material
advantages of the cientific method: clarity of communication and relative intolerance of
Research methods: general stragegies for conducting scientific studies
Experiment=manipulation of one variable under controlled conditions so that resulting changes
in another variable can be obseved
detection of cause and effect relationships
Independent vairable=variable manipulated
dependent variable=variable affected by manipulation
experimental group-subjects who receceive some special treatment in regard to the independent
Control group-SIMILAR subjects who do not receive the special treatment
2 groups alike in all respects (random)
manipulate indepentent variable for only one group
resulting differences in the two groups must be tdue to the independent variable
Extraneous and confounding variables
Expose a single group to different conditions
Reduces extraneous variables
Manipulate more than one independent variable
allows for study of interactions between variables
Use more than one dependent variable
obtains a more complete picture of effect of the independent variable
figure 2.2
conclusions about cause and effect can be drawn
artificial nature of experiments
ethical and pratical issues
Descriptive/ correlational methods
methods used when a reasearches cannot manipulate the variables under study
naturalistic obsevation
case studies
Allows researchers to describe patterns of behaviour and discover links or associating between
variables but cannot imply causation
fig 2.4----->methods on midterm
use quantitative research to draw conclusions
drawing conclusions
statistics-using mathermatics to organize and summerarize and interpret numerical data
Descriptive statistics; organizaing summarizing data
inferential statistics: interpreting data and drawing conclusions
measures of central tendency
mean-arimethic average of scores
median- score falling in the exact centre
mode-most frequent
Which most accurately depicts the typical
it depends on the data looking to achieve
descriptive statistics
variability=how much scores vary from each other and from the mean
standard deviation=numerical depiction of variability
high variability in data set-high standard deveiation
low variabilty in data set= low standard deviation
standard deviation veryimportant as mean can be
descpriptive statistics: correlation
when two variables are related to each other, they are correlated
correlation=numerical index of degree of relationship
expressed as a number between 0 and 1
can be posotive or negatitve