Statistics Dictionary

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Statistics Dictionary Absolute Value Accuracy Addition Rule Alpha Alternative Hypothesis ANOVA Back-to-Back Stemplots Balanced Design Bar Chart Bartlett's Test Bayes Rule Bayes Theorem Bias Biased Estimate Bimodal Distribution Binomial Distribution Binomial Experiment Binomial Probability Binomial Random Variable Bivariate Data Blinding Blocking Blocking Variable Bonferroni Correction Boxplot Cartesian Plane Categorical Variable Census Central Limit Theorem Chi-Square Distribution Chi-Square Goodness of Fit Test Chi-Square Statistic Chi-Square Test for Homogeneity Chi-Square Test for Independence Cluster Cluster Sampling Coefficient of Determination Coefficient of Multiple Determination Column Vector Combination Comparisons Complement Completely Randomized Design Conditional Distribution Conditional Frequency Conditional Probability Confidence Interval Confidence Level Confounding Contingency Table Continuous Probability Distribution Continuous Variable Control Group Convenience Sample Correlation Covariance Critical Parameter Value Critical Value Cumulative Frequency Cumulative Frequency Plot Cumulative Probability Decision Rule Degrees of Freedom Dependent Variable Determinant Deviation Score Diagonal Matrix Discrete Probability Distribution Discrete Variable Discriminant Analysis Disjoint Disproportionate Stratification Dotplot Double Bar Chart Double Blinding Dummy Variable E Notation Echelon Matrix Effect Size Element Elementary Matrix Operations Elementary Operators Empty Set Epsilon Error Rate Familywise Error Rate per Comparison Estimation Estimator Event Event Multiple Expected Value Experiment Experimental Design Extraneous Variable F Distribution F Statistic Factor Factorial Factorial Experiment Finite Population Correction Fixed Effects Model Fixed Factor Frequency Count Frequency Table Full Rank Gaps in Graphs Geometric Distribution Geometric Probability Hartley's Fmax Test Heterogeneous Histogram Homogeneous Hypergeometric Distribution Hypergeometric Experiment Hypergeometric Probability Hypergeometric Random Variable Hypothesis Test Identity Matrix Independent Independent Groups Design Independent Variable Influential Point Inner Product Interaction Plot Interactions Interquartile Range Intersection Interval Estimate Interval Scale Inverse IQR Joint Frequency Joint Probability Distribution Law of Large Numbers Level Line Linear Combination of Vectors Linear Dependence of Vectors Linear Transformation Logarithm Lurking Variable Margin of Error Marginal Distribution Marginal Frequency Marginal Mean Matched Pairs Design Matched-Pairs t-Test Matrix Matrix Dimension Matrix Inverse Matrix Order Matrix Rank Matrix Transpose Mauchly's Sphericity Test Mean Mean Square Measurement Scales Median Mixed Model Mode Multicollinearity Multinomial Distribution Multinomial Experiment Multiple Regression Multiplication Rule Multistage Sampling Mutually Exclusive Natural Logarithm Negative Binomial Distribution Negative Binomial Experiment Negative Binomial Probability Negative Binomial Random Variable Neyman Allocation Nominal Scale Nonlinear Transformation Non-Probability Sampling Nonresponse Bias Normal Distribution Normal Random Variable Null Hypothesis Null Set Observational Study One-Sample t-Test One-Sample z-Test One-stage Sampling One-Tailed Test One-Way ANOVA One-Way Table Optimum Allocation Ordinal Scale Orthogonal Comparisons Outer Product Outlier Paired Data Parallel Boxplots Parameter Pearson Product-Moment Correlation Percentage Percentile Permutation Placebo Planned Comparisons Point Estimate Poisson Distribution Poisson Experiment Poisson Probability Poisson Random Variable Population Post Hoc Comparisons Power Precision Probability Probability Density Function Probability Distribution Probability Sampling Proportion Proportionate Stratification P-Value Qualitative Variable Quantitative Variable Quartile Random Effects Model Random Factor Random Number Table Random Numbers Random Sampling Random Variable Randomization Randomized Block Design Randomized Block Experiment Range Ratio Scale Reduced Row Echelon Form Region of Acceptance Region of Rejection Regression Relative Frequency Relative Frequency Table Repeated Measures Design Replication Representative Residual Residual Plot Response Bias Row Echelon Form Row Vector Sample Sample Design Sample Point Sample Space Sample Survey Sampling Sampling Distribution Sampling Error Sampling Fraction Sampling Method Sampling With Replacement Sampling Without Replacement Scalar Matrix Scalar Multiple Scatterplot Scheffe Test Selection Bias Set Significance Level Simple Random Sampling Simple Regression Singular Matrix Skewness Slope Sphericity Standard Deviation Standard Error Standard Normal Distribution Standard Score Statistic Statistical Experiment Statistical Hypothesis Statistics Stemplot Strata Stratified Sampling Subset Subtraction Rule Sum Vector Sums of Squares Symmetric Matrix Symmetry Systematic Sampling T Distribution T Score T Statistic Test Statistic Transpose Treatment t-Test Two-Sample t-Test Two-stage Sampling Two-Tailed Test Two-Way Table Type I Error Type II Error Unbiased Estimate Undercoverage Uniform Distribution Unimodal Distribution Union Univariate Data Variable Variance Variance Inflation Factor Vector Inner Product Vector Outer Product Vectors Venn Diagram Voluntary Response Bias Voluntary Sample Y Intercept z-score

Factor

In an experiment, the factor (also called an independent variable) is an explanatory variable manipulated by the experimenter.

Each factor has two or more levels (i.e., different values of the factor). Combinations of factor levels are called treatments. The table below shows independent variables, factors, levels, and treatments for a hypothetical experiment.

		Vitamin C
		0 mg	250 mg	500 mg
Vitamin E	0 mg	Treatment 1	Treatment 2	Treatment 3
	400 mg	Treatment 4	Treatment 5	Treatment 6

In this hypothetical experiment, the researcher is studying the possible effects of Vitamin C and Vitamin E on health. There are two factors - dosage of Vitamin C and dosage of Vitamin E. The Vitamin C factor has three levels - 0 mg per day, 250 mg per day, and 500 mg per day. The Vitamin E factor has 2 levels - 0 mg per day and 400 mg per day. The experiment has six treatments. Treatment 1 is 0 mg of E and 0 mg of C, Treatment 2 is 0 mg of E and 250 mg of C, and so on.

See also:

Experiments