Working with Data

As an example, let's enter the following data into the calculator.

x	y
0	12.5
1	19.1
2	23.2
3	30.0
4	39.1
5	43.2

To begin, press STAT and select Edit. Enter the x-values in the L1 column, and the y-values in L2. (If there is old data in the lists that you need to clear out, put the cursor up on L1 or L2, press CLEAR, then press Enter or the down arrow to clear the list.)

To plot the data, press Y=, clear out whatever functions you have in there, arrow up to Plot1 and press Enter to turn it on. (Plot1 should be highlighted.)

Set an appropriate window, then press GRAPH.

Finding a Best-Fit Function

Select	For this type of Model
4:LinearReg(ax+b)	Linear, y=ax + b
5:QuadReg	Quadratic, y=ax² + bx + c
6:CubicReg	Cubic, y=ax³ + bx² + cx + d
9:LnReg	Logarithmic, y = a + b ln(x)
0:ExpReg	Exponential, y = a*b^x
B:Logistic	Logistic, y = c/(1 + a*e^{-b x})
C:SinReg	Sinusoidal, y = a sin(bx + c) + d

Press STAT, and arrow over to CALC. Our example (see above) looks essentially linear, so we select 4:LinearReg(ax+b).

Then press VARS, arrow over to Y-VARS, press Enter, and select Y₁. Once you have
LinReg(ax+b) Y₁ copied to the homescreen, press Enter.

In our example, the result should be the line
y = 6.294x + 12.114 (rounding to 3 decimal places).

Now press GRAPH to see a graph of the best-fit function together with the original data. To trace along the best-fit function, press TRACE, then press the down arrow (otherwise, you are tracing the scatter plot of the data, instead of the function in Y₁).