Chapter 2: Methods in Psychology 2026

3 key of the scientific attitude

curiosity: a desire to learn and explore new information

skepticism: questioning attitude not really accepting claims without sufficient evidence

humility: open minded willingness to accept that you might be wrong and to discard old ideas when the facts prove otherwise

Empirical evidence

information gathered through direct observation, experimentation, or measurable experience rather than through theory, intuition, or personal belief

Quantitative data

numbers

Quantitative data

non numerical information about lived experiences

Cognitive biases

unconscious systematic errors in thinking that distorts how people process information, make judgements and reach decisions

Confirmation Bias

tendency to favor information that supports pre-existing beliefs while disregarding or dismissing information that contradicts them

Overconfidence Bias

people tend to think they know more than they do

Hindsight bias

tendency to believe, after learning an outcome, that we could have predicted it

Hypothesis

testable falsifiable prediction, implied by a theory

Operational definitions

a precise, measurable description of how a researcher will observe, measure, or manipulate a variable during a study

Replication

repeating the essence of a research study to get the same results

Peer Review

evaluated by one’s peers in the scientific community

Falsifiable hypothesis

a testable framework that makes specific predictions which can be proven wrong by empirical observation

Convenience sampling

non probability sampling method where researchers select participants because they are easy to reach, slose, by and willing to participate

Representative Sample

smaller group of participants that accurately mirrors the key characteristics, demographics, and proportions of a larger target population

Random Sample

every member of a target population has an equal and a known chance of being chosen for a study

Wording effect

how specific phrasing or choice of works in a survey question or research study influences how participants respond

Self report bias

a methodological error that occurs when survey respondents or study participants provide inaccurate or misleading answers about their own thoughts, feelings or behaviors

Social desirability bias

the tendency of people to answer questions or present themselves in a way that aligns with social norms and looks favorable others than sharing their true thoughts, feelings, or behaviors

Case study

in depth, detailed examination of a single person, group or event

Naturalistic observation

psychologists watch and record human or animal behavior in its real world setting without interfering or manipulation any variables

Correlation

a linear relationship between 2 variables. Does not prove causation

Meta-analysis

summarizes previous studies on a topic. could summarize multiple correlational studies or experimental studies

Correlation direction

either positive or negative

Positive correlation

more is more relationship

Negative

more is less relationship

Correlation Strength

measure by the correlation coefficient

Positive correlation

Weak

Zero correlation 0:→0.5→1.0 Strong. Positive

Negative correlation

Strong

-1.0→-0.5→0 Weak. Negative

Directionally problem

inability to know which of two correlated variables causes the other

3rd Variable problem

occurs when an observed correlation or statistical relationship between two variables is actually caused by a separate, unmeasured third variable that influences both

Independent variable

the factor that a researcher intentionally changes or manipulates to see what effect it has on another factor

Dependent Variable

the outcome for behavior that a researcher measures to see the effect of changes made to the independent variable

Confounding Variable

outside factor in an experiment that changes along with your main variables and can trick you into seeing a false cause and effect relationship

Random Assignment

an experimental technique where researchers use chance procedures to place study participants into different groups

Central Tendency

mean, median and mode

Skewed Distributions

positive or negative skew

Measure of Variability

range and standard variations

Percentile Rank

percentage of scores that fall at or below a particular score

Frequency Distribution

an organized summary showing how often each score or value occurs in a set of psychological data

Central tendency

descriptive statistics that identify a single, typical value to represent the center of an entire data set

Mean

average score

Mode

most frequently occurring score

Median

half of the scores are about and half below

Normal curve(normal distribution)

symmetrical, bell shaped curve describes distribution of many types of data

Bimodal distribution

two overlapping groups

Negative Skew

negative dirrection

Normal (no skew)

a perfectly symmetrical distribution

Positive Skew

positive direction

Range

spread out a set of scores or data values is by find the difference between the highest and lowest values

Standard deviation

measures how much scores vary around the mean score

Percentile rank

percentage of scores in a distribution that are equal to or lower than a given score

Experimental Bias

when a researcher's own expectations, beliefs, or desires unintentionally influence the outcome of a study

 Observer bias

systematic errors where an researcher’s expectations, opinions, or prejudices unintentionally influence how they observe, record, or interpret data in a study

Single blind experiment

an experiment where the participants do not know if they are in the treatment group or the control group but the researchers do

Double blind experiment

neither the participant in the study nor the person giving the study know who is the control group and who is in the experimental group

placebo

a medical treatment or psychological intervention that is believed to “inet”

Placebo effect

individuals experience some type of benefit after the administration of a placebo

Sampling bias

a group of people chosen for a study does not fairly represent the wider population