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Variance and Covariance
The variance of a random variable X quantifies the spread or dispersion of the distribution of X. A random variable is essentially a function or rule that associates a number with the outcome of an experiment. Examples of random variables are an individual's weight, the number of inpatient admissions at a hospital on a single day, and a binary indicator (e.g., assigning values of 0 = no or 1 = yes) of whether or not a patient participating in a study had his or her conditions improve after taking a new drug.
The variance and its square root, the standard deviation, are important summary measures of the distribution of X and are essential for providing a complete description of X. Suppose that μX denotes the mean ...
- Basis for Making the Decision
- Acceptability Curves and Confidence Ellipses
- Beneficence
- Bioethics
- Choice Theories
- Construction of Values
- Cost-Benefit Analysis
- Cost-Comparison Analysis
- Cost-Consequence Analysis
- Cost-Effectiveness Analysis
- Cost-Minimization Analysis
- Cost-Utility Analysis
- Decision Quality
- Distributive Justice
- Dominance
- Equity
- Evaluating Consequences
- Expected Utility Theory
- Expected Value of Perfect Information
- Extended Dominance
- Health Production Function
- League Tables for Incremental Cost-Effectivenes: Ratios
- Marginal or Incremental Analysis, Cost-Effectiveness Ratio
- Monetary Value
- Moral Choice and Public Policy
- Net Benefit Regression
- Net Monetary Benefit
- Nonexpected Utility Theories
- Pharmacoeconomics
- Protected Values
- Rank-Dependent Utility Theory
- Return on Investment
- Risk-Benefit Trade-Off
- Subjective Expected Utility Theory
- Toss-Ups and Close Calls
- Value-Based Insurance Design
- Welfare, Welfarism, and Extrawelfarism
- Biostatistics and Clinical Epidemiology
- Analysis of Covariance (ANCOVA)
- Analysis of Variance (ANOVA)
- Attributable Risk
- Basic Common Statistical Tests: Chi-Square Test, t Test, Nonparametric Test
- Bayesian Analysis
- Bayesian Evidence Synthesis
- Bayesian Networks
- Bayes's Theorem
- Bias
- Bias in Scientific Studies
- Brier Scores
- Calibration
- Case Control
- Causal Inference and Diagrams
- Causal Inference in Medical Decision Making
- Conditional Independence
- Conditional Probability
- Confidence Intervals
- Confounding and Effect Modulation
- Cox Proportional Hazards Regression
- Decision Rules
- Diagnostic Tests
- Discrimination
- Distributions: Overview
- Dynamic Treatment Regimens
- Effect Size
- Equivalence Testing
- Experimental Designs
- Factor Analysis and Principal Components Analysis
- Fixed Versus Random Effects
- Frequentist Approach
- Hazard Ratio
- Hypothesis Testing
- Index Test
- Intraclass Correlation Coefficient
- Likelihood Ratio
- Logic Regression
- Logistic Regression
- Log-Rank Test
- Maximum Likelihood Estimation Methods
- Measures of Central Tendency
- Measures of Frequency and Summary
- Measures of Variability
- Meta-Analysis and Literature Review
- Mixed and Indirect Comparisons
- Multivariate Analysis of Variance (MANOVA)
- Nomograms
- Number Needed to Treat
- Odds and Odds Ratio, Risk Ratio
- Ordinary Least Squares Regression
- Parametric Survival Analysis
- Poisson and Negative Binomial Regression
- Positivity Criterion and Cutoff Values
- Prediction Rules and Modeling
- Probability
- Propensity Scores
- Randomized Clinical Trials
- Receiver Operating Characteristic (ROC) Curve
- Recurrent Events
- Recursive Partitioning
- Regression to the Mean
- Sample Size and Power
- Screening Programs
- Statistical Notations
- Statistical Testing: Overview
- Subjective Probability
- Subset Analysis: Insights and Pitfalls
- Survival Analysis
- Tables, Two-by-Two and Contingency
- Variance and Covariance
- Violations of Probability Theory
- Weighted Least Squares
- Decision Analysis and Related Mathematical Models
- Applied Decision Analysis
- Boolean Algebra and Nodes
- Decision Analyses, Common Errors Made in Conducting
- Decision Curve Analysis
- Decision Tree: Introduction
- Decision Trees, Advanced Techniques in Constructing
- Decision Trees, Construction
- Decision Trees, Evaluation
- Decision Trees, Evaluation With Monte Carlo
- Decision Trees: Sensitivity Analysis, Basic and Probabilistic
- Decision Trees: Sensitivity Analysis, Deterministic
- Declining Exponential Approximation of Life Expectancy
- Deterministic Analysis
- Discrete-Event Simulation
- Disease Management Simulation Modeling
- Expected Value of Sample Information, Net Benefit of Sampling
- Influence Diagrams
- Markov Models
- Markov Models, Applications to Medical Decision Making
- Markov Models, Cycles
- Markov Processes
- Reference Case
- Steady-State Models
- Stochastic Medical Informatics
- Subtrees, Use in Constructing Decision Trees
- Test-Treatment Threshold
- Time Horizon
- Tornado Diagram
- Tree Structure, Advanced Techniques
- Health Outcomes and Measurement
- Complications or Adverse Effects of Treatment
- Cost-Identification Analysis
- Costs, Direct Versus Indirect
- Costs, Fixed Versus Variable
- Costs, Opportunity
- Costs, Out-of-Pocket
- Costs, Semifixed Versus Semivariable
- Costs, Spillover
- Economics, Health Economics
- Efficacy Versus Effectiveness
- Efficient Frontier
- Health Outcomes Assessment
- Health Status Measurement Standards
- Health Status Measurement, Assessing Meaningful Change
- Health Status Measurement, Construct Validity
- Health Status Measurement, Face and Content Validity
- Health Status Measurement, Floor and Ceiling Effects
- Health Status Measurement, Generic Versus Condition-Specific Measures
- Health Status Measurement, Minimal Clinically Significant Differences, and Anchor Versus Distribution Methods
- Health Status Measurement, Reliability and Internal Consistency
- Health Status Measurement, Responsiveness and Sensitivity to Change
- Human Capital Approach
- Life Expectancy
- Morbidity
- Mortality
- Oncology Health-Related Quality of Life Assessment
- Outcomes Research
- Patient Satisfaction
- Regret
- Report Cards, Hospitals and Physicians
- Risk Adjustment of Outcomes
- SF-36 and SF-12 Health Surveys
- SF-6D
- Sickness Impact Profile
- Sunk Costs
- Impact or Weight or Utility of the Possible Outcomes
- Certainty Equivalent
- Chained Gamble
- Conjoint Analysis
- Contingent Valuation
- Cost Measurement Methods
- Decomposed Measurement
- Disability-Adjusted Life Years (DALYs)
- Discounting
- Discrete Choice
- Disutility
- EuroQol (EQ-5D)
- Health Utilities Index Mark 2 and 3 (HUI2, HUI3)
- Healthy Years Equivalents
- Holistic Measurement
- Multi-Attribute Utility Theory
- Person Trade-Off
- Quality of Well-Being Scale
- Quality-Adjusted Life Years (QALYs)
- Quality-Adjusted Time Without Symptoms or Toxicity (Q-TWiST)
- SMARTS and SMARTER
- Split Choice
- Utilities for Joint Health States
- Utility Assessment Techniques
- Willingness to Pay
- Other Techniques, Theories, and Tools
- Artificial Neural Networks
- Bayesian Networks
- Bioinformatics
- Chaos Theory
- Clinical Algorithms and Practice Guidelines
- Complexity
- Computer-Assisted Decision Making
- Constraint Theory
- Decision Board
- Decisional Conflict
- Error and Human Factors Analyses
- Ethnographic Methods
- Expert Systems
- Patient Decision Aids
- Qualitative Methods
- Story-Based Decision Making
- Support Vector Machines
- Team Dynamics and Group Decision Making
- Threshold Technique
- Perspective of the Decision Maker
- Advance Directives and End-of-Life Decision Making
- Consumer-Directed Health Plans
- Cultural Issues
- Data Quality
- Decision Making in Advanced Disease
- Decisions Faced by Hospital Ethics Committees
- Decisions Faced by Institutional Review Boards
- Decisions Faced by Nongovernment Payers of Healthcare: Managed Care
- Decisions Faced by Patients: Primary Care
- Decisions Faced by Surrogates or Proxies for the Patient, Durable Power of Attorney
- Diagnostic Process, Making a Diagnosis
- Differential Diagnosis
- Evaluating and Integrating Research Into Clinical Practice
- Evidence Synthesis
- Evidence-Based Medicine
- Expert Opinion
- Genetic Testing
- Government Perspective, General Healthcare
- Government Perspective, Informed Policy Choice
- Government Perspective, Public Health Issues
- Health Insurance Portability and Accountability Act Privacy Rule
- Health Risk Management
- Informed Consent
- Informed Decision Making
- International Differences in Healthcare Systems
- Law and Court Decision Making
- Medicaid
- Medical Decisions and Ethics in the Military Context
- Medical Errors and Errors in Healthcare Delivery
- Medicare
- Models of Physician–Patient Relationship
- Patient Rights
- Physician Estimates of Prognosis
- Rationing
- Religious Factors
- Shared Decision Making
- Surrogate Decision Making
- Teaching Diagnostic Clinical Reasoning
- Technology Assessments
- Terminating Treatment, Physician Perspective
- Treatment Choices
- Trust in Healthcare
- The Psychology Underlying Decision Making
- Accountability
- Allais Paradox
- Associative Thinking
- Attention Limits
- Attraction Effect
- Automatic Thinking
- Axioms
- Biases in Human Prediction
- Bounded Rationality and Emotions
- Certainty Effect
- Cognitive Psychology and Processes
- Coincidence
- Computational Limitations
- Confirmation Bias
- Conflicts of Interest and Evidence-Based Clinical Medicine
- Conjunction Probability Error
- Context Effects
- Contextual Error
- Counterfactual Thinking
- Cues
- Decision Making and Affect
- Decision Modes
- Decision Psychology
- Decision Weights
- Decision-Making Competence, Aging and Mental Status
- Deliberation and Choice Processes
- Developmental Theories
- Dual-Process Theory
- Dynamic Decision Making
- Editing, Segregation of Prospects
- Emotion and Choice
- Errors in Clinical Reasoning
- Experience and Evaluations
- Fear
- Frequency Estimation
- Fuzzy-Trace Theory
- Gain/Loss Framing Effects
- Gambles
- Hedonic Prediction and Relativism
- Heuristics
- Human Cognitive Systems
- Information Integration Theory
- Intuition Versus Analysis
- Irrational Persistence in Belief
- Judgment
- Judgment Modes
- Learning and Memory in Medical Training
- Lens Model
- Lottery
- Managing Variability and Uncertainty
- Memory Reconstruction
- Mental Accounting
- Minerva-DM
- Mood Effects
- Moral Factors
- Motivation
- Numeracy
- Overinclusive Thinking
- Pain
- Pattern Recognition
- Personality, Choices
- Preference Reversals
- Probability Errors
- Probability, Verbal Expressions of
- Problem Solving
- Procedural Invariance and Its Violations
- Prospect Theory
- Range-Frequency Theory
- Risk Attitude
- Risk Aversion
- Risk Communication
- Risk Perception
- Scaling
- Social Factors
- Social Judgment Theory
- Stigma Susceptibility
- Support Theory
- Uncertainty in Medical Decisions
- Unreliability of Memory
- Value Functions in Domains of Gains and Losses
- Worldviews
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