Using the data below, calculate the bias based on using the naive forecast method:

Week

$1$

$2$

$3$

$4$

Time Series Value

$24\mathrm{.}00$

$17\mathrm{.}00$

$19\mathrm{.}00$

$8\mathrm{.}00$

Answer format: Number: Round to: $1$ decimal places.