7 Line of Best FitA line you draw on a graph to approximate the relationship between data sets.Also called a trend lineA line of best fit should have an equal number of data points on each sideIf there is no correlation, you cannot draw a line of best fit
8 You Try! Create a scatter plot for the data and draw the trend line. 2 5433.574.596
9 Making Predictions What is the approximate weight of a 7 month old panda?We have just used interpolation toestimate a value between two known values using a line of best fit.Extrapolation is used to predict a value outside the range of known values.Ex: Use your model to find the body weight of a 3-year old panda.
10 CausationA change in one quantity causes a change in the second quantity.Correlation does not always imply causation
11 Using a CalculatorCorrelation coefficient (r) can be found using a graphing calculator.Ranges between -1 and 1The nearer r is to 1 or -1, the more closely the trend line fits the datar close to 1 shows a strong positive correlationr close to -1 shows a strong negative correlationr close to 0 means a weaker correlation or no correlation
12 Using a Calculator Press STAT and then 1 to select EDIT Enter x-values into L1 and y-values into L2(if x-values are years, do not enter the year, but enter 1 for one year from the start, 2 for 2 years from start, etc.)Press STAT then move Right to the CALC menuMove Down to LinReg(ax+b) and press EnterPress Enter againa will represent slopeb will represent the y-interceptAnd r will show the correlation coefficient (NOT r2)