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Placebo
When conducting a double-blind clinical trial to evaluate a new treatment, the investigator is faced with the problem of what to give the control group. If there is no existing acceptable and beneficial treatment against which the new treatment can be compared, the reasonable approach would be to give the control group no treatment at all, but this raises concerns that subjects may have hidden expectations or preferences that could influence the outcome. One solution is the use of a harmless “sham” treatment that is similar in all aspects such that the subjects and those administering the treatments cannot determine whether a subject is in the study group or the control group. This sham treatment is called the placebo. This entry discusses historical usage, ...
- Descriptive Statistics
- Distributions
- Graphical Displays of Data
- Hypothesis Testing
- p Value
- Alternative Hypotheses
- Beta
- Critical Value
- Decision Rule
- Hypothesis
- Nondirectional Hypotheses
- Nonsignificance
- Null Hypothesis
- One-Tailed Test
- Power
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- Significance Level, Concept of
- Significance Level, Interpretation and Construction
- Significance, Statistical
- Two-Tailed Test
- Type I Error
- Type II Error
- Type III Error
- Important Publications
- “Coefficient Alpha and the Internal Structure of Tests”
- “Convergent and Discriminant Validation by the Multitrait–Multimethod Matrix”
- “Meta-Analysis of Psychotherapy Outcome Studies”
- “On the Theory of Scales of Measurement”
- “Probable Error of a Mean, The”
- “Psychometric Experiments”
- “Sequential Tests of Statistical Hypotheses”
- “Technique for the Measurement of Attitudes, A”
- “Validity”
- Aptitudes and Instructional Methods
- Doctrine of Chances, The
- Logic of Scientific Discovery, The
- Nonparametric Statistics for the Behavioral Sciences
- Probabilistic Models for Some Intelligence and Attainment Tests
- Statistical Power Analysis for the Behavioral Sciences
- Teoria Statistica Delle Classi e Calcolo Delle Probabilità
- Inferential Statistics
- Q-Statistic
- R2
- Association, Measures of
- Coefficient of Concordance
- Coefficient of Variation
- Coefficients of Correlation, Alienation, and Determination
- Confidence Intervals
- Margin of Error
- Nonparametric Statistics
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- Parameters
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- Partial Correlation
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- Intervention
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- Placebo
- Replication
- Research
- Research Design Principles
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- Sampling
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- Theories, Laws, and Principles
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- Classical Test Theory
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- Critical Theory
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- Item Response Theory
- Occam's Razor
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- Probability, Laws of
- Theory
- Theory of Attitude Measurement
- Weber–Fechner Law
- Types of Variables
- Validity of Scores
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