mankiw's macroeconomics modules A PowerPointTutorial to Accompany macroeconomics, 5th ed. N. Gregory Mankiw ® BAB 13 PENAWARAN AGREGAT

Overview Bab sebelumnya : Pemintaan Agregat Bab 9 : AS jk panjang, vertikal, harga fleksibel AS jk pendek, horizontak, harga kaku Bab 13 : mendefinisikan kembali AS jk pendek

3 MODEL terkenal untuk menjelaskan AS (karena ekonomi tidak sepakat ttg cara terbaik menjelaskan) Kesimpulan Umum : Kurva AS jk pendek berbentuk miring ke atas.

13.1 TIGA MODEL PENAWARAN AGREGAT “KENAPA AS JK PENDEK MIRING KE ATAS?”

MODEL UPAH KAKU Penyebab : lambannya penyesuaian upah nominal (kaku dalam jk pendek) Apa yang terjadi pd output jika tingkat harga naik? Upah nominal tidak berubah → upah riil turun, TK menjadi lebih murah Perusahaan akan menggunakan lebih banyak TK Produksi output lebih banyak Jadi ada hubungan positif antara tingkat harga dan output → AS miring ke atas.

Gbr (a) Kurva permintaan TK Gbr (a) Kurva permintaan TK. Kenaikan tingkat harga, menurunkan upah riil, mengakibatkan meningkatkan jumlah TK yang diminta. Gbr (b) Fungsi produksi, kenaikan TK, menaikkan output Gbr (c) AS: meringkas hub tingkat harga dgn output

Y=f(L) Y W/P L P AS L=Ld Y L

Penetapan upah nominal W = ω X Pe Upah nominal = upah riil target tingkat harga diharapkan Perusahaan mempelajari tingkat harga aktual P W/P = ω X (Pe/P) Upah riil = upah riil target X tingkat harga diharapkan Tingkat harga aktual Upah riil menyimpang dari targetnya jika tingkat harga aktual berbeda dari tingkat harga yang diharapkan

Kurva penawaran agregat Y = Y + α (P - Pe) Output menyimpang dari tingkat alamiahnya bila tingkat harga menyimpang dari harga yg diharapkan

MODEL INFORMASI TAK SEMPURNA Harga bebas menyesuaikan diri. Kurva jk pendek dan panjang berbeda karena kesalahan persepsi temporer mengenai harga. Asumsi: Setiap pemasok memproduksi barang tunggal, mengkonsumsi banyak barang. Pemasok tidak dapat mengamati seluruh harga barang, tetapi memantau dengan ketat barang produksinya. Akibat informasi yang tidak sempurna, kenaikan tingkat harga yang menyebabkan kenaikan harga nominal output produksinya, membuat pemasok menduga bahwa harga relatifnya telah naik. Akibatnya pemasok akan memproduksi lebih banyak output yang dihasilkannya.

. Model INFORMASI TAK SEMPURNA ini menyatakan bahwa bila harga aktual melebihi harga yang diharapkan, para pemasok meningkatkan output mereka

MODEL HARGA KAKU Perusahaan menghadapi harga yang kaku. Harga yang diinginkan perusahaan p tergantung : Tingkat harga keseluruhan P. P tgg, mk biaya tgg, tingkat harga perusahaan makin besar Tingkat pendapatan agregat Y. Y tgg, AD tgg, makin tgg harga yang diharapkan perusahaan.

MODEL HARGA KAKU Harga yang diinginkan perusahaan, p : p = P + α (Y - Y) tergantung tingkat harga keseluruhan P dan pada tingkat output agregat relative terhadap tingkat alamiah Y – Y.

So ? Ke3 Model AS ini tidak saling bertentangan, kita tidak perlu menerima satu model dan menolak lainnya.

REFRESH… Semua bisa diringkas : Y = Y + α (P - Pe) Output menyimpang dari tingkat alamiahnya bila tingkat harga menyimpang dari harga yg diharapkan Jika tingkat harga lebih tgg dr harga yg diharapkan, mk output melebihi tingkat alamiah. Jika harga lebih rendah dr harga yg diharapkan, mk output turun lebih rendah tingkat alamiah.

Gbr 13.2. SRAS (Pe=P2) B P2 A' Y' SRAS (Pe=P0) P Output A P0 LRAS* Y AD AD' P1

Pergeseran AD Ttk A : ekuilibrium jangka panjang. AD↑ secara tidak diharapkan, harga naik P1 ke P2. Harga P2 diatas harga yang diharapkan Pe, output naik secara temporer. Ekonomi bergerak dari A ke B. Jangka panjang, harga yang diharapkan naik ke P3e, AS jk pendek bergeser keatas, ekonomi kembali ekuilibrium, ke tingkat alamiah. .

13.2 INFLASI, PENGANGGURAN DAN KURVA PHILLIPS Kebijakan ek makro : inflasi rendah, pengangguran rendah, tapi seringkali bertentangan. Misal Mll fiskal/moneter AD ditingkatkan. Ekonomi bergerak sepanjang kurva AD ke titik output lebih tgg dan harga lebih tgg. (Gbr 13.4. Dari A ke B) Output lebih tinggi, pengangguran lebih rendah. Tingkat harga lebih tgg, berarti inflasi lebih tgg.

Tradeoff antara inflasi dan pengangguran : kurva Phillips ; merupakan derivasi AS jk pendek.

Persamaannya : Tingkat inflasi tergantung : Inflasi yang diharapkan Deviasi pengangguran dari tingkat alamiah (pengangguran siklis) Guncangan penawaran Persamaannya : π = πe - β ( µ - µn) + v inflasi = inflasi - (β X pengangguran siklis) + guncangan yg diharapkan penawaran β = respon inflasi terhadap pengangguran siklis. (tanda minus: pengangguran tgg, mengurangi inflasi)

Menderivasi kurva Phillips dari AS P = Pe + (1-α) (Y - Y) Tambahkan guncangan penawaran, menunjukkan peristiwa eksogen (mis perubahan harga minyak dunia) mengubah harga, menggeser AD jk pendek. P = Pe + (1-α) (Y - Y) + v

Merubah dari tk harga menjadi tk inflasi (P- P-1) = (Pe - P-1) + (1-α) (Y - Y) + v π = πe + (1-α) (Y - Y) + v

Okun Law Beralih dari output ke pengangguran. Hukum Okun: Penyimpangan output dari tingkat alamiah berbanding terbalik dengan penyimpangan pengangguran dari tingkat alamiah. Maka : (1-α) (Y - Y) = - β ( µ - µn) π = πe - β ( µ - µn) + v

Kv Phillips : pengangguran terkait dengan pergerakan yang tidak diharapkan dalam tingkat inflasi. AS dan kv Phillips : 2 sisi mata uang yang sama

EKSPEKTASI ADATIF DAN INERSIA INFLASI Penyebab inflasi yang diharapkan? Orang membentuk ekspektasi inflasi berdasarkan inflasi yang sedang diamati ( ekspektasi adaptif) Misal : πe = π-1 Maka kurva Phillips : π = π-1 - β ( µ - µn) + v1 Inflasi tergantung inflasi yang lalu, pengangguran siklis dan guncangan penawaran. .

EKSPEKTASI ADATIF DAN INERSIA INFLASI (tk pengangguran alamiah = NAIRU = Non-Accelerating Inflation Rate of Unemployment) Simbol π-1 menunjukkan bahwa inflasi memiliki inersia. Yaitu akan terus bergerak jika tidak ada sesuatu yang menghentikannya. Inersia inflasi diinterpretasikan sebagai pergeseran ke atas secara terus menerus dalam kv AD dan kv AS

DUA PENYEBAB NAIK & TURUNNYA INFLASI Simbol kedua, β ( µ - µn) menunjukkan penggangguran siklis (penyimpangan pengangguran dari tingkat alamiah) memberi tekanan ke atas dank e bawah pada inflasi. Pengangguran rendah → inflasi ke atas ; inflasi tarikan permintaan (inflasi karena permintaan tinggi). β responsivitas inflasi trerhadap penganggurang siklis Simbol ketiga, v menunjukkan Inflasi juga naik dan turun karena guncangan penawaran. Misalnya kenaikan harga minyak, nilai v positif, inflasi naik. Disebut inflasi dorongan biaya.

TRADE-OFF JK PENDEK INFLASI DAN PENGANGGURAN Pembuat kebijakan mempengaruhi AD. Inflasi yang diharapkan dan guncangan penawaran bisa saja berada di luar kendali pembuat kebijakan. Namun dengan mengubah AD → dapat mengubah output, pengangguran dan inflasi. Jadi pd kv Phillips jk pendek, dipilih kombinasi inflasi dan pengangguran. Gbr 13.3.

Gbr 13.3. П Пe + n un Unemployment, u

Posisi kurva Phillips jangka pendek tergantung tingkat inflasi yang diharapkan. Jika inflasi yang diharapkan naik, kurva bergeser ke atas, trade-off kebijakan menjadi kurang bernilai karena inflasi akan lebih tinggi pada seluruh tingkat pengangguran.

Gbr 13.4.  10% 5% un Unemployment, u LRPC (u=un) SRPC (e=10%)

Jangka panjang : ekspektasi akan beradaptasi pada setiap tingkat inflasi dipilih pembuat kebijakan, pengangguran kembali ke tingkat alamiah, dan tidak ada tradeoff antara inflasi dan pengangguran. Disinflasi dan Rasio Pengorbanan Menurunkan inflasi → berapa output akan hilang? Biaya ini bisa dibandingkan dengan manfaat inflasi yang lebih rendah. Rasio Pengorbanan: % GDP riil 1 tahun yang harus dikorbankan untuk menurunkan inflasi 1%.

Concluding Remarks Ada 3 model menerangkan AS jangka pendek miring ke atas. Prediksinya sama : tradeoff jk pendek antara inflasi dan pengangguran. Cara mudah menganalisi melalui kurva Phillips, yang menyatakan inflasi tergantung inflasi yang diharapkan, pengangguran siklis dan guncangan penawaran.

thank you

The Production Function Labor, L Y = F(L) Income, Output, Y L = Ld (W/P) Y=Y+a(P-Pe) The Production Function Aggregate Supply Labor Demand real wage, W/P Price level, P The Sticky-Wage Model An increase in the price level, reduces the real wage for a given nominal wage, which raises employment and output and income.

P = Pe + [(1-s)a/s](Y-Y)] The two terms in this equation are explained as follows: 1) When firms expect a high price level, they expect high costs. Those firms that fix prices in advance set their prices high. These high prices cause the other firms to set high prices also. Hence, a high expected price level Pe leads to a high actual price level P. 2) When output is high, the demand for goods is high. Those firms with flexible prices set their prices high, which leads to a high price level. The effect of output on the price level depends on the proportion of firms with flexible prices. Hence, the overall price level depends on the expected price level and on the level of output. Algebraic rearrangement puts this aggregate pricing equation into a more familiar form: where a = s/[(1-s)a]. Like the other models, the sticky-price model says that the deviation of output from the natural rate is positively associated with the deviation of the price level from the expected price level. Y = Y + a(P-Pe)

Short-run Aggregate Supply Curve in ACTION Y = Y + a (P-Pe) SRAS (Pe=P2) B P2 A' Y' SRAS (Pe=P0) P Output A P0 LRAS* Y AD AD' P1 Start at point A; the economy is at full employment Y and the actual price level is P0. Here the actual price level equals the expected price level. Now let’s suppose we increase the price level to P1. Since P (the actual price level) is now greater than Pe (the expected price level) Y will rise above the natural rate, and we slide along the SRAS (Pe=P0) curve to A' . Remember that our new SRAS (Pe=P0) curve is defined by the presence of fixed expectations (in this case at P0). So in terms of the SRAS equation, when P rises to P1, holding Pe constant at P0, Y must rise. Y = Y + a (P-Pe) The “long-run” will be defined when the expected price level equals the actual price level. So, as price level expectations adjust, PeP2, we’ll end up on a new short-run aggregate supply curve, SRAS (Pe=P2) at point B. Hooray! We made it back to LRAS, a situation characterized by perfect information where the actual price level (now P2) equals the expected price level (also, P2). In terms of the SRAS equation, we can see that as Pe catches up with P, that entire “expectations gap” disappears and we end up on the long run aggregate supply curve at full employment where Y = Y. Y = Y + a (P-Pe)

Deriving the Phillips Curve From the Aggregate Supply Curve The Phillips curve in its modern form states that the inflation rate depends on three forces: 1) Expected inflation 2) The deviation of unemployment from the natural rate, called cyclical unemployment 3) Supply shocks These three forces are expressed in the following equation: p = pe - b(m-mn) + n Expected Inflation Supply Shock Inflation b  Cyclical Unemployment

The Phillips-curve equation and the short-run aggregate supply equation represent essentially the same macroeconomic ideas. Both equations show a link between real and nominal variables that causes the classical dichotomy (the theoretical separation of real and nominal variables) to break down in the short run. The Phillips curve and the aggregate supply curve are two sides of the same coin. The aggregate supply curve is more convenient when studying output and the price level, whereas the Phillips curve is more convenient when studying unemployment and inflation.

To make the Phillips curve useful for analyzing the choices facing policymakers, we need to say what determines expected inflation. A simple often plausible assumption is that people form their expectations of inflation based on recently observed inflation. This assumption is called adaptive expectations. So, expected inflation pe equals last year’s inflation p-1. In this case, we can write the Phillips curve as: which states that inflation depends on past inflation, cyclical unemployment, and a supply shock. When the Phillips curve is written in this form, it is sometimes called the Non-Accelerating Inflation Rate of Unemployment, or NAIRU. The term p-1 implies that inflation has inertia-- meaning that it keeps going until something acts to stop it. In the model of AD/AS, inflation inertia is interpreted as persistent upward shifts in both the aggregate supply curve and aggregate demand curve. Because the position of the SRAS will shift upwards overtime, it will continue to shift upward until something changes inflation expectations. p = p-1 - b(m-mn) + n

Two Causes of Rising and Falling Inflation The second and third terms in the Phillips-curve equation show the two forces that can change the rate of inflation. The second term, b(u-un), shows that cyclical unemployment exerts downward pressure on inflation. Low unemployment pulls the inflation rate up. This is called demand-pull inflation because high aggregate demand is responsible for this type of inflation. High unemployment pulls the inflation rate down. The parameter b measures how responsive inflation is to cyclical unemployment. The third term, n shows that inflation also rises and falls because of supply shocks. An adverse supply shock, such as the rise in world oil prices in the 70’s, implies a positive value of n and causes inflation to rise. This is called cost-push inflation because adverse supply shocks are typically events that push up the costs of production. A beneficial supply shock, such as the oil glut that led to a fall in oil prices in the 80’s, makes n negative and causes inflation to fall.

The Short-Run Tradeoff Between Inflation and Unemployment In the short run, inflation and unemployment are negatively related. At any point in time, a policymaker who controls aggregate demand can choose a combination of inflation and unemployment on this short-run Phillips curve. p pe + n un Unemployment, u

The Phillips Curve in ACTION Let’s start at point A, a point of price stability (=0%) and full employment (u=un). Remember, each short-run Phillips curve is defined by the presence of fixed expectations. Suppose there is an increase in the rate of growth of the money supply causing LM and AD to shift out resulting in an unexpected increase in inflation. The Phillips curve equation  = e – b(u-un) + v implies that the change in inflation misperceptions causes unemployment to decline. So, the economy moves to a point above full employment at point B. As long as this inflation misperception exists, the economy will remain below its natural rate un at u'. un  Unemployment, u LRPC (u=un) 5% 10% SRPC (e=0%) SRPC (e=10%) SRPC (e=5%) When the economic agents realize the new level of inflation, they will end up on a new short-run Phillips curve where expected inflation equals the new rate of inflation (5%) at point C, where actual inflation (5%) equals expected inflation (5%). D E If the monetary authorities opt to obtain a lower u again, then they will increase the money supply such that  is 10%, for example. The economy moves to point D, where actual inflation is 10% but, e is 5%. B C u' When expectations adjust, the economy will land on a new SRPC, at point E, where both  and e equal 10%. A

Rational Expectations and the Possibility of Painless Disinflation Rational expectations make the assumption that people optimally use all the available information about current government policies, to forecast the future. According to this theory, a change in monetary or fiscal policy will change expectations, and an evaluation of any policy change must incorporate this effect on expectations. If people do form their expectations rationally, then inflation may have less inertia than it first appears. Proponents of rational expectations argue that the short-run Phillips curve does not accurately represent the options that policymakers have available. They believe that if policy makers are credibly committed to reducing inflation, rational people will understand the commitment and lower their expectations of inflation. Inflation can then come down without a rise in unemployment and fall in output.

Hysteresis and the Challenge to the Natural-Rate Hypothesis Our entire discussion has been based on the natural rate hypothesis. The hypothesis is summarized in the following statement: Fluctuations in aggregate demand affect output and employment only in the short run. In the long run, the economy returns to the levels of output,employment, and unemployment described by the classical model. Recently, some economists have challenged the natural-rate hypothesis by suggesting that aggregate demand may affect output and employment even in the long run. They have pointed out a number of mechanisms through which recessions might leave permanent scars on the economy by altering the natural rate of unemployment. Hyteresis is the term used to describe the long-lasting influence of history on the natural rate.

Key Concepts of Ch. 13 Sticky-wage model Imperfect-information model Sticky-price model Phillips curve Adaptive expectations Demand-pull inflation Cost-push inflation Sacrifice ratio Rational expectations Natural-rate hypothesis Hyteresis