1.19:

1.19: Significancia estadística

Statistical Significance

JoVE Core
Social Psychology

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JoVE Core Social Psychology

Statistical Significance

1.18: Variation: Normal Distribution, Range, and Standard Deviation

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01:50 min

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February 12, 2020

Overview

Once data is collected from both the experimental and the control groups, a statistical analysis is conducted to find out if there are meaningful differences between the two groups. A statistical analysis determines how likely any difference found is due to chance (and thus not meaningful). In psychology, group differences are considered meaningful, or significant, if the odds that these differences occurred by chance alone are 5 percent or less. Stated another way, if we repeated this experiment 100 times, we would expect to find the same results at least 95 times out of 100.

The greatest strength of experiments is the ability to assert that any significant differences in the findings are caused by the independent variable. This occurs because random selection, random assignment, and a design that limits the effects of both experimenter bias and participant expectancy should create groups that are similar in composition and treatment. Therefore, any difference between the groups is attributable to the independent variable, and now we can finally make a causal statement. If we find that watching a violent television program results in more violent behavior than watching a nonviolent program, we can safely say that watching violent television programs causes an increase in the display of violent behavior.

Transcript

Después de que los investigadores recopilan datos empíricos de un tamaño de muestra predeterminado, pueden hacer un seguimiento con análisis estadísticos para determinar si las diferencias que observaron entre grupos o variables son significativas o solo el resultado del azar.

Por ejemplo, tal vez un investigador encuentre que los estudiantes de pregrado a los que se les pidió que usaran el gesto y la expresión emocional para representar una escena, el grupo experimental, recordaban más de sus líneas que los estudiantes que las leyeron sin usar el gesto y la expresión emocional, el grupo de control.

Ahora quiere saber la probabilidad de que esta diferencia ocurriera porque la manipulación experimental afectó la memoria de los participantes para las líneas, en lugar de debido a una casualidad aleatoria.

Para llevar a cabo esta tarea, necesita establecer el valor p, es decir, la probabilidad de que la diferencia entre los grupos haya ocurrido por casualidad.

Si encuentra que el valor p es de 0,05 o menos, lo que significa que hay un cinco por ciento o menos de posibilidades de que el resultado haya ocurrido por casualidad, entonces la diferencia entre los grupos se considera estadísticamente significativa por convención.

En otras palabras, hay al menos un 95 por ciento de probabilidades de que los participantes en el grupo experimental recordaran más líneas debido a la manipulación experimental, utilizando el gesto y la expresión emocional.

Como resultado, puede aceptar con confianza la hipótesis alternativa o experimental (que la manipulación experimental afectó los resultados) y rechazar la hipótesis nula (que la manipulación experimental no tuvo ningún efecto).

Al final, si se determina que los hallazgos de la investigación son estadísticamente significativos, la comunidad científica considera que los resultados son diferencias significativas.

Key Terms and definitions

Statistical analysis - Formal process of investigating relationships among variables, applied in psychology.
Statistically significant - A measure of the likelihood that the difference is explaining by chance.
P-value - A statistical term for the probability that an observed result occurred by chance.
Significant difference - Noticeable variance between groups, not likely to be purely by chance.
Independent variable - The variable in the experiment that is manipulated, causing an effect.

Learning Objectives

Define Statistical analysis - Explain how it is used in psychology (e.g., statistical analysis).
Contrast statistically significant vs. P-value - Explain what sets these two terms apart (e.g., significant difference).
Explore p-value - Describe its role in statistical analysis (e.g., p-value).
Explain independent variable - Discuss its influence in an experiment.
Apply significant difference - Contextualize this on experimental scenarios.

Questions that this video will help you answer

What is statistical analysis and how is it applied in psychology?
What is the difference between statistically significant and p-value?
How is p-value used when conducting statistical analysis?

This video is also useful for

Students - Understand how statistical analysis supports learning in experimental psychology
Educators - Provides a clear framework for teaching statistical analysis in psychology
Researchers - Relevance of statistical significance and p-value in scientific studies
Psychology Enthusiasts - Offer insights about statistical analysis and its significance in psychology

Tags

Significación Estadística Datos Empíricos Tamaño de la Muestra Análisis Estadísticos Diferencias Entre Grupos o Variables Diferencias Significativas Solo Azar Grupo Experimental Grupo Control Valor P Probabilidad Ocurrencia Casual Estadísticamente Significativo Manipulación Experimental Hipótesis Alternativa