Sampling & Types of Bias
A cognitive bias that leads individuals to favor information that confirms their preexisting beliefs or hypotheses. People tend to ignore or undervalue evidence that contradicts their views.
Confirmation Bias
The group in an experiment that receives the treatment or intervention being tested.
Experimental Group
A testable statement or prediction about the relationship between two or more variables. It serves as a foundation for conducting research and forming conclusions based on empirical evidence.
Hypothesis
A detailed and in-depth examination of a single subject or a small group of subjects, often used to explore complex issues or phenomena in real-life contexts. It can involve various data collection methods, including interviews, observations, and analysis of documents.
Case Study
A graphical representation of data distribution where data is divided into intervals or bins. The height of each bar represents the frequency or count of data points within each interval.
Histogram
The arithmetic average of a data set, calculated by summing all values and dividing by the number of values.
Mean
The tendency to perceive events as having been more predictable than they actually were after the events have occurred. It’s often summarized by the phrase "I knew it all along."
Hindsight Bias
The group that does not receive the treatment or intervention and is used as a baseline for comparison to assess the effect of the treatment.
Control Group
A hypothesis that can be proven wrong through evidence or experimentation. It must be possible to conduct an experiment or gather data that could potentially refute the hypothesis.
Falsifiable Hypothesis
A research method where the researcher observes and records behavior in its natural environment without manipulating or controlling the situation. This method aims to provide a realistic view of behavior in real-world settings.
Naturalistic Observation
A type of graph that shows the relationship between two quantitative variables, with each point representing an observation. It helps to visualize the strength and direction of the relationship between the variables.
Scatterplot
The middle value in a data set when values are ordered from least to greatest. If there is an even number of values, the median is the average of the two middle values.
Median
The phenomenon where individuals overestimate their own abilities, knowledge, or predictions. This can lead to a misjudgment of one's own level of competence or the accuracy of forecasts.
Overconfidence
An inactive substance or treatment that is used as a control in experiments to compare against the actual treatment.
Placebo
Detailed descriptions of how variables will be measured and observed in a study. These definitions ensure that abstract concepts are defined in concrete, measurable terms.
Operational Definitions
The process of providing potential research participants with sufficient information about a study to make an informed decision about their participation.
Informed Consent
A numerical value (ranging from -1 to +1) that quantifies the strength and direction of the linear relationship between two variables. Positive values indicate a positive relationship, while negative values indicate an inverse relationship.
Correlational Coefficient
The value that appears most frequently in a data set. A set can have one mode, more than one mode, or no mode at all.
Mode
The distortion in a sample that occurs when certain members of the population are more likely to be included than others. This can lead to a non-representative sample and affect the validity of the results.
Sampling Bias
The variable that is measured and observed to see if it changes as a result of manipulations to the independent variable. It is the presumed effect.
Dependent Variable
A technique used in experimental research where participants are randomly assigned to different groups (such as treatment and control groups) to ensure that each participant has an equal chance of being placed in any group, which helps to eliminate biases and confounding variables.
Random Assignment
Ensuring that research participants are not exposed to physical or psychological harm.
Protection from Harm
A symmetrical, bell-shaped curve representing the distribution of a set of standardized data. In this curve:
Standard Normal Curve
The difference between the highest and lowest values in a data set.
Range
The process of applying findings from a sample to the larger population. Generalization is valid when the sample accurately represents the population.
Generalization
The variable that is manipulated or controlled by the researcher to observe its effect on another variable. It is the presumed cause in an experiment.
Independent Variable
The entire group of individuals or items that researchers are interested in studying. It represents the complete set from which a sample might be drawn.
Population
The process of informing participants about the true nature and purpose of the study after their participation, especially if deception was used. It also involves addressing any concerns and ensuring participants’ well-being.
Debriefing
About 68% of data falls within one standard deviation of the mean, 95% within two standard deviations, and 99.7% within three standard deviations.
Percentages of Distributions
A measure of the dispersion of data points around the mean. It quantifies the average distance of each data point from the mean.
Standard Deviation
A sampling method where participants are selected based on their easy accessibility and proximity to the researcher, which may introduce biases and limit generalizability.
Convenience Sampling
Extraneous variables that the researcher did not control for, which can affect the dependent variable and lead to inaccurate conclusions about the relationship between the independent and dependent variables
Confounding Variables
An experiment where the participants do not know whether they are receiving the treatment or the placebo, but the researchers do.
Single-Blind
The assurance that personal information collected during research will be kept private and not disclosed without permission.
Confidentiality
Describes the asymmetry of the distribution. A normal curve has no skewness (it is perfectly symmetrical). Positive skew indicates a long tail on the right, while negative skew indicates a long tail on the left.
Skewness
The percentage of scores in a data set that fall below a given score, indicating the relative standing of that score within the distribution.
Percentile Rank
A sample in which every member of the population has an equal chance of being selected. This method helps ensure that the sample is representative and reduces sampling bias.
Random Sample
The situation where an unexamined variable influences both the independent and dependent variables, making it difficult to determine the true relationship between them.
Third Variable Problem
An experiment where neither the participants nor the researchers know who is receiving the treatment or the placebo, which helps to minimize biases.
Double-Blind
Deception involves misleading participants about the true nature of the study. When used, it must be justified and participants must be debriefed afterward.
Deception/Confederates
A distribution with two distinct peaks or modes, indicating that there are two different groups or clusters within the data.
Bimodal Distribution
The measure of how spread out the data points are in a data set. It indicates the extent of dispersion or diversity among the values.
Variation
A subset of the population that accurately reflects the characteristics of the larger group. It allows for generalization of results to the population.
Representative Sample
The process by which other experts in the field evaluate a researcher’s work before it is published to ensure its validity, significance, and originality.
Peer Review
Research methods that involve collecting in-depth, non-numerical data through detailed interviews with predetermined questions.
Qualitative (Structured Interviews)
Guidelines and regulations governing the humane treatment and care of animals used in research. These standards ensure that animal research is conducted ethically and with minimal harm.
Animal Research Ethical Standards
A statistical relationship between two variables, showing how they change together. Correlation does not imply causation; it only indicates whether and how strongly pairs of variables are related.
Correlation
The difference between the highest and lowest values.
Range
A form of bias that occurs when the researcher’s expectations or preferences influence the outcome of the study or the interpretation of data.
Experimenter Bias
The process of repeating a study to verify its results and confirm the reliability and validity of the findings.
Replication
Research methods that involve numerical data and statistical analysis. These scales are a common tool where respondents indicate their level of agreement or disagreement with statements on a scale, such as from "strongly agree" to "strongly disagree."
Quantitative Measures (Likert Scales)
A statistical technique that combines the results of multiple independent studies on the same topic to determine overall trends and derive more generalizable conclusions. It helps to increase the statistical power and reliability of findings.
Meta-Analysis
The average of the squared differences from the mean.
Variance
The tendency for participants to respond in a manner they believe will be viewed favorably by others, often leading to distorted or inaccurate responses.
Social Desirability Bias
A measure indicating whether the results of a study are likely due to chance or if they reflect a true effect. It is often determined using p-values, with values below a certain threshold (e.g., 0.05) considered statistically significant.
Statistical Significance
The tendency for participants to provide inaccurate or distorted responses in self-report measures, often due to social desirability, recall bias, or other factors.
Self-Report Bias
The phenomenon where extreme scores or measurements tend to be closer to the average upon subsequent measurement. This effect is more pronounced when more data is collected and can be attributed to random variability.
Regression Toward the Mean
The square root of the variance, representing the average distance of each data point from the mean.
Standard Deviation