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An online coefficient of determination calculator helps you determine the R-squared value (coefficient of determination) for two datasets. This R value calculator evaluates the strength of the linear relationship between the independent and dependent variables and predicts how well future outcomes may be estimated. In the following sections, you will learn what R-squared is and how to calculate it using the R-squared formula.
The coefficient of determination, denoted as R², is a statistical measure derived from regression analysis. It shows how well the regression model explains the variation of the observed data points. An R² value close to 1 indicates that the model explains most of the variability in the dependent variable. It is a key indicator of model fit and can be calculated using either correlation coefficients or regression outputs. Additionally, a Coefficient of Variation Calculator can complement this analysis by showing variability relative to the mean.
Correlation Coefficient formula:
r = Σ [(X − X̄) * (Y − Ȳ)] / √{ [Σ (X − X̄)² * Σ (Y − Ȳ)²] }
Then,
R² = (Correlation Coefficient)²
Where:
R² can also be calculated from regression sums:
Where:
Here, Ŷ represents the predicted value, Ȳ is the mean of observed Y, and Yi is the ith observed value. You can also use a Covariance Calculator to compute covariance between X and Y for additional analysis.
Consider two datasets: (10, 20, 30, 40, 50) and (12, 18, 33, 37, 55).
Using an R-squared calculator, the coefficient of determination can be calculated step by step.
| Obs. | X | Y | X² | Y² | X·Y |
|---|---|---|---|---|---|
| 1 | 10 | 12 | 100 | 144 | 120 |
| 2 | 20 | 18 | 400 | 324 | 360 |
| 3 | 30 | 33 | 900 | 1089 | 990 |
| 4 | 40 | 37 | 1600 | 1369 | 1480 |
| 5 | 50 | 55 | 2500 | 3025 | 2750 |
| Sum | 150 | 155 | 5500 | 5951 | 6660 |
Number of values (n) = 5
Compute the sums of squares:
SSxx = ΣX² − (ΣX)² / n = 5500 − (150² / 5) = 5500 − 4500 = 1000
SSyy = ΣY² − (ΣY)² / n = 5951 − (155² / 5) = 5951 − 4805 = 1146
SSxy = Σ(X·Y) − (ΣX·ΣY) / n = 6660 − (150·155 / 5) = 6660 − 4650 = 2010
Correlation coefficient:
R = SSxy / √(SSxx·SSyy) = 2010 / √(1000·1146) ≈ 2010 / 1070 = 0.941
Coefficient of determination:
R² = (0.941)² ≈ 0.886
For linear regression Y ~ aX + b, the square of the correlation coefficient equals R², showing how much of Y's variability is explained by X.
R² ranges from 0 to 1. Multiply by 100 to express as a percentage. For the example above, 88.6% of the variation in Y is explained by X. A high R² indicates a strong linear relationship, but it does not imply causation.
Enter your datasets in separate fields, separated by commas, and click calculate.
R² close to 1 indicates a model that fits the data well and predicts future outcomes reliably. Values near 0 indicate poor fit.
In multiple regression, R² measures the proportion of variance in the dependent variable explained by all independent variables combined.
The correlation coefficient, r, shows both the strength and direction of a linear relationship between two variables. It ranges from -1 (perfect negative) to +1 (perfect positive), with 0 indicating no linear correlation.
The non-determination coefficient = 1 − R². It represents the portion of variance not explained by the regression model.
The R² calculator computes the correlation coefficient and coefficient of determination for your data. It shows the percentage of variance explained and provides multiple calculation methods, giving a clear understanding of the relationship between variables.
Wikipedia: Coefficient of determination; Investopedia: Understanding R²; Stat Trek: Linear regression.
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