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

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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

goal

◦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

happiness)

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

error

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

variable

Control group-SIMILAR subjects who do not receive the special treatment

◦Logic

▪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

Strengths:

◦conclusions about cause and effect can be drawn

Weaknesses

◦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

◦survey's

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

variablility

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

## Document Summary

50 mc choice arrive at 6:20 and write for 1 hour. Data collection techniques allow for empirical observation and measurement. 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 variable. 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. Strengths: conclusions about cause and effect can be drawn. Weaknesses: artificial nature of experiments, ethical and pratical issues. Methods used when a reasearches cannot manipulate the variables under study: naturalistic obsevation, case studies, survey"s.