Quantitative Research SPED 500 Dr. Sandra Beyda Designs that maximize objectivity by using numbers, statistics, structure, and experimenter control Modes.

Quantitative Research

SPED 500

Dr. Sandra Beyda

• Designs that maximize objectivity by using numbers, statistics, structure, and experimenter control

• Modes– Experimental mode– Non-experimental

mode

Structure of a Data Based Study

• Abstract• Introduction• Method• Results• Discussion• Summary & Conclusions• References

True experiment

Quasi-experimental

Single Subject

True Experiments

• Internal validity

• External validity– Randomization– Systematically vary or manipulate– Hold constant– Assume invariance or irrelevance– Matching– Statistical control

Threats to Internal Validity

When there is a statistically significant result (X > Control)

History MaturationTesting

Nonequivalence

Regression

Mortality

Interactions with Selection

Instrumentation

Threats to Internal Validity

When there are non-significantly different results:

Small sample size

Treatment implementation

Insensitive dependent variable

John Henry EffectTreatment not long enough

Treatment diffusion

Threats to External Validity

• Population validity• Ecological validity• Operations validity

• Posttest only • Pretest-Posttest• Solomon 4 Group Design• Factorial Design

• No Random Assignment!

• One group• Time series approach

• Two groups• Static group comparison

• Non-equivalent control group

• Reliable measurements

• Repeated measurements

• Baseline

• Introduction of treatment

• Reversal or withdrawal

• Maintenance• Replication

Single Subject Research Designs

AB

ABAABAB

Multiple Baseline

How about a little practice exercise?

Don’t worry. I’ll wait!

• Descriptive

• Comparative

• Correlational

• Ex Post Facto

Descriptive Research

• Single Group• Cross-sectional• Longitudinal

Comparative Research

Correlational Research

• Purpose: What is the relationship between variable A and B?

• Uses:– Theory building

– Establish predictive relationships

Correlational Research

• Bivariate correlational studies

• Prediction studies– Predictor variable

– Criterion variable

Correlational Research Limitations

• Correlation and Causation

• Spurious Correlations

• Size of Correlation Coefficients

• Purpose: – To examine how an identified independent

variable effects the dependent variable when circumstances do not allow for the manipulation of the independent variable

• Conditions for establishing cause-effect connections – (1) statistical significance-– (2) IV before DV. – (3) Alternative causes

Ex-Post Facto ResearchDesigns

• Single Group• Between Group

• Problems– Self selection

– Correlation-causation fallacy

– Direction of causality