# SOAN 2120 Lecture Notes - Lecture 1: Random Number Generation, Equivalent Average, Random Assignment

by OC1195303

School

University of GuelphDepartment

Sociology and AnthropologyCourse Code

SOAN 2120Professor

D WaltersLecture

1This

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Experimental Designs

Experimental Research- Chapter 7

Independent variable -> dependent variable (differences in outcomes

between two groups)

Equivalent

-average scores on the dependent variable and

-scores on all other variables which are likely to impact the dependent

variable

Differences: manipulation

If there are different results it is because of different treatments

How do we establish the equivalence of two (or more) groups?

Random number generator

Objective: equal probability of assignment

Essential – the groups are equivalent

Conclusion: Manipulation

Event with RA the two (or more) groups will not be exactly in all respects.

Random individual variations).

If the assignment is random, we can use tests of statistical significance

(manipulation vs. random variation)

As the sample size increases, individual differences decline

Without RA: Findings may be attributable to pre-existing differences

between the groups

What is this called>

We could compare pre-test scores (dependent variable measures) before the

experiment begins

-Significantly different? ->equivalent -> proceed as if random assignment

had taken place

What about all other potential confounding variables?

This happens automatically with random assignment

Standard Notation: pg173

R O1 X O2

R O3 O4

X represents an experimental variable or effect the independent variable

O represents a dependent variable observation. Subscripts (scripts) depict

the observation; the exact ordering of the numbering is somewhat

unimportant

This experiment has a pre-test and a post-test

The pre-test for the experimental group (O1)

The pre-test for the control group (O3)

Finally, the letter R denotes RA

Simulated driving video game to assess the impact of various substances on

driving impairments

Group 1; 6 crashes (weed)

find more resources at oneclass.com

find more resources at oneclass.com

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