Experimental Methods - Slide Deck 3

How psychologists collect data

Data Collection Methods: Study Design / Methods (3/3)

Different types of studies that are typically used in psychology to collect data

• Naturalistic Observation

• Case-Studies

• Correlational Studies

• Experiments

• Meta-Analyses

Data Collection Methods: Correlational Studies (3/3)

Estimate the numerical prediction between two measured variables (3/3)

Ex. Is there a relationship between age and political party affiliation

Correlational Study: Procedure (3/3)

1. Choose any two variables

2. Measure them with an instrument in as largest sample possible

3. Graph their relationship using all available data

4. Estimate the direction and strength of their correlation

A correlation between two variables does not mean that one necessarily causes the other

Correlational Studies: Positive Correlation (3/3)

A relationship wherein the increase of one variable is associated with the increase of the other variable

Ex. More hours studied leads to higher test scores.

Correlational Studies: No Correlation (3/3)

A relationship wherein the variables are not associated with changes in one another

Correlational Studies: Negative Correlation (3/3)

A relationship wherein the increase in one variable is associated with a decrease in the other (vice versa)

Ex. More sleep is associated with less stress

Flaws of Correlational Studies: Directionality Problem (3/3)

For any correlation A may have caused B, or. B may have caused A, there is no way to know

Flaws of Correlational Studies: Third Variable Problem (3/3)

For any correlation, a third, unmeasured variable may have been the true cause of the measured ones

Correlational Studies: Spurious Correlations (3/3)

Strongly correlated variables that we know for certainty are not causally related

Ex. Number of films Nicolas Cage appeared in and number of deaths by drowning in a pool

Data Collection Methods: Experiments (3/3)

A research method wherein one variable is manipulated or changed (independent variable) to see its causal effects on another variable (dependent variable) with the presence of an unaffected group (control group)

Experiments: Random Assignment (3/3)

A key component of this method wherein participants are randomly assigned into experimental and control groups

Experiments: Random Selection (3/3)

A key component of this method wherein participants should be representative of the population as a whole and chosen without bias

Benefits of Experiments Method: Directionality (3/3)

Having the ability to control the variables being manipulated and measured allows researchers to control direction

Benefits of Experiments Method: Third-Variable Problem (3/3)

The two groups should be theoretically identical in every third variable, so the only difference between the two groups is the one the researchers decide

Data Collection Methods: Meta-Analysis (3/3)

The process of aggregating data from many different studies (typically 5-20 studies with published results) and combining them to get a more precise result