Regression Models

Warm-Up Activity
Finding a Linear Regression Model

\begin{tabular}{|c|c|}
\hline
[tex]$x$[/tex] & [tex]$y$[/tex] \\
\hline
-4 & -6 \\
\hline
-1 & -1 \\
\hline
0 & 1 \\
\hline
2 & 4 \\
\hline
3 & 7 \\
\hline
\end{tabular}

Find a linear function that models the data in the table.

[tex]\[ f(x) = \square x + \square \][/tex]



Answer :

To find a linear function that models the data given in the table, we need to determine the slope (m) and the intercept (b) of the linear equation in the form [tex]\( f(x) = mx + b \)[/tex].

Given the data points:
[tex]\[ \begin{array}{|c|c|} \hline x & y \\ \hline -4 & -6 \\ \hline -1 & -1 \\ \hline 0 & 1 \\ \hline 2 & 4 \\ \hline 3 & 7 \\ \hline \end{array} \][/tex]

1. Calculate the slope (m):

The slope of a line through two points [tex]\((x_1, y_1)\)[/tex] and [tex]\((x_2, y_2)\)[/tex] is given by:
[tex]\[ m = \frac{y_2 - y_1}{x_2 - x_1} \][/tex]

However, since we need the best fit line through multiple points, we use a method that averages out the differences for all points. Without delving into the manual calculations (like calculating the covariance of [tex]\(x\)[/tex] and [tex]\(y\)[/tex] and the variance of [tex]\(x\)[/tex]), we can state the computed slope from the aggregated calculations.

[tex]\[ m \approx 1.800 \][/tex]

2. Calculate the intercept (b):

Once the slope is determined, we use the formula for the intercept:
[tex]\[ b = \bar{y} - m\bar{x} \][/tex]
where [tex]\(\bar{y}\)[/tex] is the mean of the [tex]\(y\)[/tex]-values and [tex]\(\bar{x}\)[/tex] is the mean of the [tex]\(x\)[/tex]-values.

Similarly, summarizing the calculations:

[tex]\[ b \approx 1.000 \][/tex]

3. Construct the linear equation:

Now that we have both the slope and intercept, we can construct our linear function.
[tex]\[ f(x) = 1.800x + 1.000 \][/tex]

Therefore, the linear function that models the data in the table is:
[tex]\[ f(x) = 1.800x + 1.000 \][/tex]