Psychology Chapter on Correlation and Experiments

Correlation

• Correlation does not equal causation
• Correlations predict
• Correlation coefficient is an index of the relationship between two things from -1 to +1

Types of Correlation

• Positive correlation- variables moving in the same direction
• Negative correlation- variables moving in opposite directions

Experimental Method

• One variable manipulated and the rest controlled
• Independent variable is manipulated
• Dependent variable is measured
• Confounding variable influences independent and dependent variables, causing a spurious association
• Operational definitions define variables in terms of measurement or manipulation

Participants in Experiments

• Experimental group receives treatment
• Control groups do not receive treatment
• Random assignment minimizes preexisting differences between groups by assigning participants to groups by chance

Experimenter Bias

• Researchers influence results to portray a desired outcome

Types of Blind Studies

• Single-blind study- participants are unaware of group assignment, researchers are aware
• Double-blind study- both participants and researchers are unaware of group assignment

Placebo Condition

• Participants believe they are receiving treatment, but no treatment is administered

Sampling

• Sample is a subset of a population
• Representative sample accurately reflects population characteristics
• Random sample gives each member an equal chance of inclusion
• Sample bias occurs when some members of the population have a lower chance of inclusion

Generalizability

• This is the extent to which results of a study can be applied to others

Statistics

• Branch of math dealing with analyzing numerical data
• Descriptive statistics summarize collected data
• Inferential statistics allow for predictions and inferences about a population based on a sample

Measures of Central Tendency

• Single value representing an entire distribution
• Mean is the average
• Median is the middle value
• Mode is the most frequent value

Other Measures

• Range is the difference between highest and lowest values
• Normal curve is a bell-shaped curve representing frequencies concentrated around the mean
• Regression to the mean is the tendency for extreme measurements to be closer to the average on subsequent measurements

Skew

• Positive skew- more values on the lower side with a few high values
• Negative skew- more values on the higher side with a few low values

Standard Deviation

• Measure of variation or dispersion in a set of values

Percentile Rank

• Percentage of scores equal to or lower than a given score

Bimodal Distribution

• Distribution with two peaks or modes in frequency of occurrences

Statistical Significance

• Results are probably true or just due to chance
• Determines if the observed result would occur often or rarely when nothing special is happening

Effect Size

• Measures the impact or effect of something
• Shows how much a treatment helps compared to no treatment

Meta-Analysis

• Statistical analysis combining results of multiple studies

Institutional Review Boards (IRB)

• Review and approve research involving human subjects ensuring ethical standards are met

Explore the fundamental concepts of correlation and the experimental method in psychology. This quiz covers the distinctions between positive and negative correlations, the role of independent and dependent variables, and the impact of experimenter bias. Test your understanding of how researchers structure experiments to minimize bias and accurately interpret data.