Skor Komposit EWS (0-100)
\[
S_t = w_1 T_t + w_2 P_t + w_3 V_t + w_4 B_t,\quad \sum_{i=1}^4 w_i = 1
\]
Ambang alert: Kuning \( \ge 55 \), Merah \( \ge 75 \).
Bobot yang digunakan: \(w_1=0.35,\; w_2=0.35,\; w_3=0.20,\; w_4=0.10\).
Keterangan: \(S_t\)=skor EWS waktu \(t\); \(T_t\)=rata-rata skor tren lintas komoditas aktif; \(P_t\)=rata-rata skor pressure; \(V_t\)=rata-rata skor volatilitas; \(B_t\)=breadth; \(w_i\)=bobot komponen.
Pembobotan Komoditas (IHK SBH 2022)
\[
\alpha_j=\frac{\omega^{IHK}_j}{\sum_{k=1}^{N_t}\omega^{IHK}_k},\quad \sum_{j=1}^{N_t}\alpha_j=1
\]
\[
T_t=\sum_{j=1}^{N_t}\alpha_j T_{j,t},\quad
P_t=\sum_{j=1}^{N_t}\alpha_j P_{j,t},\quad
V_t=\sum_{j=1}^{N_t}\alpha_j V_{j,t}
\]
\[
B_t=100\times\sum_{j=1}^{N_t}\alpha_j\mathbf{1}\!\left(\Delta^{7d}_{j,t}\ge\theta_j\ \lor\ P_{j,t}>\tau_j^{HET/HA}\right)
\]
Keterangan: \(\omega^{IHK}_j\)=bobot diagram timbang komoditas \(j\); \(\alpha_j\)=bobot normalisasi komoditas aktif; \(\mathbf{1}(\cdot)\)=indikator 1 jika status Waspada, 0 jika Normal; \(\theta_j\)=ambang waspada tren; \(\tau_j^{HET/HA}\)=batas harga kebijakan HET/HA untuk komoditas yang memiliki ketentuan.
Trend 7 Hari (indeks)
\[
T_t = \mathrm{Norm}\!\left(100\left(\frac{P_t}{P_{t-7}} - 1\right)\right)
\]
Keterangan: \(P_t\)=harga hari ini; \(P_{t-7}\)=harga 7 hari lalu; \(\mathrm{Norm}(\cdot)\)=normalisasi ke skala indeks 0-100 berbasis fungsi eksponensial \((k=2.5)\).
Pressure vs Baseline (indeks)
\[
P_t = \mathrm{Norm}\!\left(100\left(\frac{P_t}{\mu_{30,t}} - 1\right)\right),\quad
\mu_{30,t} = \frac{1}{30}\sum_{i=0}^{29} P_{t-i}
\]
Keterangan: \(P_t\)=harga hari ini; \(\mu_{30,t}\)=rata-rata bergerak 30 hari; \(P_{t-i}\)=harga historis ke-\(i\) hari ke belakang; \(\mathrm{Norm}(\cdot)\) eksponensial \((k=2.0)\).
Volatilitas 30 Hari (indeks)
\[
V_t = \frac{1}{N_t}\sum_{j=1}^{N_t}\mathrm{Norm}\!\left(\sigma_{30}(r_{j,t})\right),\quad
r_{j,t}=\left(\frac{P_{j,t}}{P_{j,t-1}}-1\right)\times 100
\]
Keterangan: \(N_t\)=jumlah komoditas aktif (contoh: 52); \(j\)=komoditas ke-\(j\); \(r_{j,t}\)=return harian komoditas \(j\); \(\sigma_{30}\)=simpangan baku return 30 hari; \(\mathrm{Norm}(\cdot)\) eksponensial \((k=1.5)\).
Breadth Komoditas (%)
\[
B_t = \frac{N_{\mathrm{Waspada},t}}{N_{\mathrm{Total},t}}\times 100
\]
Keterangan: \(N_{\mathrm{Waspada},t}\)=jumlah komoditas status Waspada; \(N_{\mathrm{Total},t}\)=total komoditas dipantau pada waktu \(t\).