- Write the equation using the two points you found in step 3. 4th Ex 1 Draw a scatter plot of the data. Then approximate the best fitting line for the data X 0 0.5 1 2.5 3.5 4 5 2 Y 4 3 2.5 2.5 -1 -3 The best fit line was drawn in blue approx. half the points above – and below the line. Then, write the equation of the line using your two points. Using the points (0, 2.5) and (4, -2.5), find the slope. and the y-intercept is 2.5. My line of best fit is: Correlation Correlation measures the strength and direction of the linear relationship between two quantitative variables. The numerical measure we use is called the correlation coefficient and its symbol is It measures how tightly the points on a r. . scatterplot cluster about a straight line. The formula is The good news is that technology can calculate this value for us and the formula will not be used. Facts about correlation: Correlation makes no distinction between explanatory and response variables. It makes no difference which variable is graphed on the x-axis and which is on the y-axis. Correlation requires that both variables be quantitative (not categorical). r does not change if the values of either variable are converted to a different scale. Example: if all the measures are changed from feet to inches, r doesn’t change. r has no units of measure. It is just a number. r is always a value between -1 and +1, inclusive. Extreme values () indicate a perfect straight line association. Values of r near 0 indicate a very weak linear relationship. The strength of the relationship increases as r moves away from 0 toward -1 or +1. Correlation measures the strength of only a LINEAR relationship between two variables. It does not describe nonlinear relationships.
4th - Write the equation using the two points you found in step 3. Ex 1 Draw a scatter plot of the data. Then approximate the best fitting line for the data X 0 0.5 1 2.5 3.5 4 5 Y 4 3 2.5 2.5 2 -1 -3 The best fit line was drawn in blue – approx. half the points above and below the line. Then, write the equation of the line using your two points. Using the points (0, 2.5) and (4, -2.5), find the slope. and the y-intercept is 2.5. My line of best fit is: Correlation Correlation measures the strength and direction of the linear relationship between two quantitative variables. The numerical measure we use is called the correlation coefficient and its symbol is r. It measures how tightly the points on a scatterplot cluster about a straight line. The formula is . The good news is that technology can calculate this value for us and the formula will not be used. Facts about correlation: Correlation makes no distinction between explanatory and response variables. It makes no difference which variable is graphed on the x-axis and which is on the y-axis. Correlation requires that both variables be quantitative (not categorical). r does not change if the values of either variable are converted to a different scale. Example: if all the measures are changed from feet to inches, r doesn’t change. r has no units of measure. It is just a number. r is always a value between -1 and +1, inclusive. Extreme values () indicate a perfect straight line association. Values of r near 0 indicate a very weak linear relationship. The strength of the relationship increases as r moves away from 0 toward -1 or +1. Correlation measures the strength of only a LINEAR relationship between two variables. It does not describe nonlinear relationships.
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