In this video I explain how a frequency distribution can create a visual representation of our data. I also describe a normal curve or “bell curve” and what it means for mean, median, and mode. Then I consider skewed distributions … Read More
Understanding Significance and P-values
In this video I explain the concept of significance and how it relates to both effect size, sample size, and the law of large numbers. The role of a p-value in describing the likelihood of data is explained with an … Read More
Measures of Variance: Range and Standard Deviation
In this video I describe two more descriptive statistics, both of which are measures of variance: the range and the standard deviation. I explain what the standard deviation tells us about a distribution of scores and how it is calculated. … Read More
Difference between a Theory and a Hypothesis
In this video I describe the difference between a theory and a hypothesis. I also explain how evidence can support or refute a hypothesis but can never prove a theory. Don’t forget to subscribe to the channel to see future … Read More
The Experimental Method
In this video I explain the experimental method and how the combination of manipulation and random assignment can help to eliminate the third variable problem. I also explain why random assignment helps avoid self-selection and bias so that we can … Read More
The Third Variable Problem
In this video I explain the third variable problem in correlational studies, how matched samples and matched pairs can be used to eliminate a possible third variable, and why measurement alone can never truly solve the third variable problem. Don’t … Read More
Real and Illusory Correlations, Scatterplots, and Causation
In this video I explain the dangers of illusory correlations and confirmation bias, correlational studies, patterns of variation, r-values, scatterplots and conclusions about causation. Try guessing the r-value from a scatterplot at www.guessthecorrelation.com Don’t forget to subscribe to the channel … Read More
Populations and Samples
In this video I explain populations and samples, including random sampling, opportunity samples, stratified sampling, and issues related to representativeness. Don’t forget to subscribe to the channel to see future videos! Have questions or topics you’d like to see covered … Read More
Operational Definitions and Construct Validity
In this video, I cover properties, operational definitions, and construct validity. Understanding these concepts is fundamental for determining which conclusions can be drawn from a study and should always be kept in mind when considering interpretations of research. Don’t forget … Read More
Observer Bias: Clever Horses and Dull Rats
In this video, I explain two well-known examples of observer bias: the case of Clever Hans, and Rosenthal and Fode’s experiment with “bright” and “dull” rats. Observer bias (or experimenter expectancy effect) is considered, along with an explanation for how … Read More