A hidden Markov model for predicting global stock market index

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The Korean Journal of Applied Statistics 2021, Vol. 34, No. 3, 461โ€“475 DOI: https://doi.org/10.5351/KJAS.2021.34.3.461 Print ISSN1225-066X / Online ISSN 2383-5818 A hidden Markov model for predicting global stock market index Hajin Kang a , Beom Seuk Hwang 1, a a Department of Applied Statistics, Chung-Ang University Abstract Hidden Markov model (HMM) is a statistical model in which the system consists of two elements, hidden states and observable results. HMM has been actively used in various ๏ฌelds, especially for time series data in the ๏ฌnancial sector, since it has a variety of mathematical structures. Based on the HMM theory, this research is intended to apply the domestic KOSPI200 stock index as well as the prediction of global stock indexes such as NIKKEI225, HSI, S&P500 and FTSE100. In addition, we would like to compare and examine the di๏ฌ€erences in results between the HMM and support vector regression (SVR), which is frequently used to predict the stock price, due to recent developments in the arti๏ฌcial intelligence sector. Keywords: global stock market index, hidden Markov model, KOSPI200, stock index prediction, support vector regression 1. โ€˜ 1%X โ€น หœ, โ€ž \รผ T\19\ xt mยท 0โ€น 1% l<\ โ€ฐ t 8| t รผ @ x U\ H<\ ยทXp, \ ,| t D, รผ ` รฆรผ@ โ€น/l| \ 5 `D ยท , L<\ \'X$ 5 D t ยท . \, ,โ€” \ mT Tt 50รผ 0ยฏโ€” Dยจ| x ,หœ X D HXtLหœ tx ,โ€” \ t D . รผยฅ@ ยฅ LXtหœ โ€˜ t 5 ยฅ `iD Eโ€˜ t. KOSPI200 รผ \mD \X รผ 200 'X aD T\ <\ 1990D 1 3| 100D 0<\ โ€ฆยจ ยจ| ยทp, ,โ€” \ /Xยจl \\ โ€น' mยท \ t. รผยฅt ยท/ PD โ€ฆ !X @ โ€ฐ 5 ยฅ !โ€” Iยฅ \ tp, )t รผ !โ€” \'ยท \ l . l lโ€” รผ X(, t( รฆรผ@ หœ pt0โ€” i\ @ ยจtT ยคx(hidden Markov model; HMM)Dt'tยฅหœ !โ€” 'X \. mยท tx รผ| 'X \X ยคxD \t t| t ยฅหœX| 0X รผยฅโ€” \ t )ยฅ1 lโ€น `โ€” \ !t ยฅโ€˜ t. This research was supported by the Chung-Ang University Research Scholarship Grants in 2020. 1 Corresponding author: Department of Applied Statistics, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, Korea. E-mail: [email protected] Published 30 June 2021 / journal homepage: http://kjas.or.kr ยฉ 2021 The Korean Statistical Society. All rights reserved.

Transcript of A hidden Markov model for predicting global stock market index

Page 1: A hidden Markov model for predicting global stock market index

The Korean Journal of Applied Statistics2021, Vol. 34, No. 3, 461โ€“475

DOI: https://doi.org/10.5351/KJAS.2021.34.3.461Print ISSN1225-066X / Online ISSN 2383-5818

A hidden Markov model for predicting global stock marketindex

Hajin Kanga, Beom Seuk Hwang1,a

aDepartment of Applied Statistics, Chung-Ang University

Abstract

Hidden Markov model (HMM) is a statistical model in which the system consists of two elements, hiddenstates and observable results. HMM has been actively used in various fields, especially for time series data inthe financial sector, since it has a variety of mathematical structures. Based on the HMM theory, this research isintended to apply the domestic KOSPI200 stock index as well as the prediction of global stock indexes such asNIKKEI225, HSI, S&P500 and FTSE100. In addition, we would like to compare and examine the differencesin results between the HMM and support vector regression (SVR), which is frequently used to predict the stockprice, due to recent developments in the artificial intelligence sector.

Keywords: global stock market index, hidden Markov model, KOSPI200, stock index prediction, supportvector regression

1.์„œ๋ก 

์—ฐ 1%๋Œ€์˜์ €๊ธˆ๋ฆฌ์‹œ๋Œ€๊ฐ€๊ณ„์†๋˜๊ณ ,ํŠนํžˆ์ตœ๊ทผ์ฝ”๋กœ๋‚˜19๋กœ์ธํ•ด๊ตญ๋‚ด๊ธฐ์ค€๊ธˆ๋ฆฌ๊ฐ€ 1%๋ฏธ๋งŒ์œผ๋กœ๋ณ€๊ฒฝ๋ฐ์œ ์ง€๋˜๋ฉด์„œ์ž์‚ฐ๋ณดํ˜ธ๋ฅผ์œ„ํ•ด์„œ๋Š”๊ธˆ๊ณผ๋ถ€๋™์‚ฐ๊ฐ™์€๋‹ค๋ฅธํ™•์‹คํ•œ์•ˆ์ „์ž์‚ฐ์œผ๋กœ๋Œ€์ฒดํ•˜๊ฑฐ๋‚˜,๋ฐ˜๋Œ€๋กœํˆฌ์ž๋ฅผ์œ„ํ•ด์„œ๋Š”์ฑ„๊ถŒ,์ฃผ์‹๋˜๋Š”ํŒŒ์ƒ์ƒํ’ˆ๋“ฑ๊ณผ๊ฐ™์€๋ฆฌ์Šคํฌ๋ฅผ๋™๋ฐ˜ํ•œ๊ธˆ์œต์ƒํ’ˆ์„๋Œ€์ฒดํˆฌ์ž์ˆ˜๋‹จ์œผ๋กœํ™œ์šฉํ•˜๋ ค๋Š”๊ธˆ์œต์†Œ๋น„์ž๋“ค์ด ๋Š˜์–ด๋‚˜๊ณ  ์žˆ๋‹ค. ๋˜ํ•œ, ํˆฌ์ž์— ๋Œ€ํ•œ ๊ตญ์ œํ™”๊ฐ€ ์‹ฌํ™”๋˜๋ฉด์„œ ๊ธˆ์œต๊ธฐ๊ด€๊ณผ ๊ธฐ์—…๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ๊ฐœ์ธ ํˆฌ์ž์ž๋„ํ™˜ ์œ„ํ—˜์„ ๊ฐ์•ˆํ•˜๋ฉด์„œ๊นŒ์ง€๋„ ํ•ด์™ธ ํˆฌ์ž์— ๋Œ€ํ•œ ๊ด€์‹ฌ์ด ๋†’์•„์ง€๊ณ  ์žˆ๋‹ค. ์ฃผ์‹ ์‹œ์žฅ์€ ๊ฐ€์žฅ ๊ฐ„๋‹จํ•˜๋ฉด์„œ๋„ ๋น ๋ฅด๊ฒŒ ๊ธˆ์œต ์‹œ์žฅ ์ƒํ™ฉ์„ ํŒŒ์•…ํ•  ์ˆ˜ ์žˆ๋Š” ๊ณณ์ด๋‹ค. KOSPI200 ์ฃผ๊ฐ€์ง€์ˆ˜๋Š” ํ•œ๊ตญ์„ ๋Œ€ํ‘œํ•˜๋Š” ์ฃผ์‹ 200๊ฐœ ์ข…๋ชฉ์˜์‹œ๊ฐ€์ด์•ก์„์ง€์ˆ˜ํ™”ํ•œ๊ฒƒ์œผ๋กœ 1990๋…„ 1์›” 3์ผ 100์„๊ธฐ์ค€์œผ๋กœ์–ผ๋งˆ๋‚˜๋ณ€๋™๋˜์—ˆ๋Š”์ง€๋ฅผ๋‚˜ํƒ€๋‚ด๋ฉฐ,ํˆฌ์ž์—๋Œ€ํ•œ๋ฒค์น˜๋งˆํฌ ์ง€ํ‘œ๋กœ ์‚ฌ์šฉ๋˜๋Š” ๊ตญ๋‚ด ๋Œ€ํ‘œ ์ง€์ˆ˜์ด๋‹ค. ์ฃผ์‹ ์‹œ์žฅ์ด ์–ด๋–ค ํ๋ฆ„์„ ๋‚˜ํƒ€๋‚ผ์ง€ ์˜ˆ์ธกํ•˜๋Š” ๊ฒƒ์€ ๊ฒฝ์ œ ๋ฐ๊ธˆ์œต์‹œ์žฅ์˜ˆ์ธก์—๊ต‰์žฅํžˆ์ค‘์š”ํ•œ๋ถ€๋ถ„์ด๋ฉฐ,์—ฌ๋Ÿฌ๊ฐ€์ง€๋ฐฉ๋ฒ•๋“ค์ด์ฃผ๊ฐ€์˜ˆ์ธก์—ํ™œ์šฉ๋˜์–ดํ™œ๋ฐœํžˆ์—ฐ๊ตฌ๋˜๊ณ ์žˆ๋‹ค.

๋ณธ์—ฐ๊ตฌ์—์„œ๋Š”์ฃผ๊ฐ€๋ฐํ™˜์œจ,์ด์ž์œจ๋“ฑ๊ณผ๊ฐ™์€์‹œ๊ณ„์—ด๋ฐ์ดํ„ฐ์—์ ํ•ฉํ•œ์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ(hidden Markovmodel; HMM)์„์ด์šฉํ•ดํ–ฅํ›„์˜ˆ์ธก์—์ ์šฉํ•˜๊ณ ์žํ•œ๋‹ค.์‹ค์ œ๊ตญ๋‚ด๋ฐํ•ด์™ธ์ฃผ๊ฐ€์ง€์ˆ˜๋ฅผ์ ์šฉํ•˜์—ฌ์ตœ์ ์˜๋ชจ๋ธ์„์ถ”์ •ํ•œ๋‹ค๋ฉด์ด๋ฅผํ†ตํ•ด์„œํ–ฅํ›„์˜์ผ์ •๊ธฐ๊ฐ„์˜์ฃผ์‹์‹œ์žฅ์—๋Œ€ํ•œ์ถ”์ด๋ฐ๋ฐฉํ–ฅ์„ฑ๊ทธ๋ฆฌ๊ณ ์›€์ง์ž„์—๋Œ€ํ•œ์˜ˆ์ธก์ด

๊ฐ€๋Šฅํ• ๊ฒƒ์ด๋‹ค.

This research was supported by the Chung-Ang University Research Scholarship Grants in 2020.1 Corresponding author: Department of Applied Statistics, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul

06974, Korea. E-mail: [email protected]

Published 30 June 2021 / journal homepage: http://kjas.or.krยฉ 2021 The Korean Statistical Society. All rights reserved.

Page 2: A hidden Markov model for predicting global stock market index

462 Hajin Kang, Beom Seuk Hwang

์Œ์„ฑ์ธ์‹ ๋ถ„์•ผ์—์„œ ์ฃผ๋กœ ํ™œ์šฉ๋˜๊ธฐ ์‹œ์ž‘ํ•œ ์€๋‹‰ ๋งˆ๋ฅด์ฝ”ํ”„ ๋ชจ๋ธ์€ ์œ ์ „ํ•™๊ณผ ์ƒ๋ฌผ์ •๋ณดํ•™์„ ํฌํ•จํ•œ ๋‹ค์–‘ํ•œ

๋ถ„์•ผ์—์„œ ์‹œ๊ณ„์—ด์˜ ํŒจํ„ด์„ ํ™œ์šฉํ•˜๋Š” ๋„๊ตฌ๋กœ ๋„๋ฆฌ ์ด์šฉ๋˜๊ณ  ์žˆ์œผ๋ฉฐ ๊ธˆ์œต ๊ด€๋ จ ๋ฐ์ดํ„ฐ ๋ถ„์„์—์„œ๋„ ํ™œ๋ฐœํ•˜๊ฒŒ

์‚ฌ์šฉ๋˜๊ณ ์žˆ๋‹ค (Zucchini๋“ฑ, 2017).์˜ต์…˜์˜๊ฐ€๊ฒฉ๊ฒฐ์ •๊ณผ LIBOR์‹œ์žฅ์˜๋ชจ๋ธ์—ฐ๊ตฌ๊ทธ๋ฆฌ๊ณ ์ด์ž์œจ์˜๊ธฐ๊ฐ„๊ตฌ์กฐ๋ชจ๋ธ ๊ตฌ์ถ•๊ณผ ๊ด€๋ จํ•ด์„œ๋„ HMM์ด ํ™œ๋ฐœํ•˜๊ฒŒ ์ด์šฉ๋˜์–ด ์™”๋‹ค (Mamon๊ณผ Elliott, 2007). ๋˜ํ•œ, HMM์„ ํ™œ์šฉํ•œ์ฑ„๊ถŒ๊ฐ€๊ฒฉ์‚ฐ์ถœ (Landen, 2000)๋ฐ์€ํ–‰๊ณ ๊ฐ์„๊ตฐ์ง‘ํ™”ํ•˜๋Š”์—ฐ๊ตฌ๋„์ง„ํ–‰๋˜์—ˆ์œผ๋ฉฐ (Knab๋“ฑ, 2003),์ฃผ์‹๊ฐ€๊ฒฉ์—๋Œ€ํ•œ์˜ˆ์ธก์—๋„ HMM์ดํ™œ์šฉ๋˜์–ด์™”๋‹ค (Hassan๊ณผ Nath, 2005).

๋ณธ๋…ผ๋ฌธ์—์„œ๋Š” HMM๋ฐฉ๋ฒ•์„๊ตญ๊ฐ€๋ณ„์ฃผ๊ฐ€์ง€์ˆ˜์˜ˆ์ธก์—์ ์šฉํ•ด๋ณด๊ณ ์žํ•œ๋‹ค.๋จผ์ € AIC, BIC, HQC (Hannan๊ณผQuinn, 1979), CAIC (Bozdogan, 1987)์™€๊ฐ™์€์ •๋ณด๊ธฐ์ค€์„์‚ฌ์šฉํ•˜์—ฌHMM์˜์ตœ์ ์˜์ƒํƒœ์˜์ˆ˜๋ฅผ๊ฒฐ์ •ํ•œ๋‹ค.๊ทธํ›„ HMM์˜๋ชจ์ˆ˜์ถ”์ •์—์‚ฌ์šฉ๋˜๋Š”ํ›ˆ๋ จ๋ฐ์ดํ„ฐ์—๋Œ€ํ•˜์—ฌ์ข…๊ฐ€,์‹œ๊ฐ€,๊ณ ๊ฐ€,์ €๊ฐ€๋ฅผ์ด์šฉํ•˜์—ฌ Hassan๊ณผ Nath(2005)์˜๋ฐฉ๋ฒ•์„์ ์šฉํ•˜๊ณ ์žํ•œ๋‹ค.์‹ค์ œ๋ฐ์ดํ„ฐ๋กœ๋Š”๊ตญ๋‚ด KOSPI200์ฃผ๊ฐ€์ง€์ˆ˜์™€์ผ๋ณธ์˜ NIKKEI225,ํ™์ฝฉ์˜HSI, ๋ฏธ๊ตญ์˜ S&P500, ์˜๊ตญ์˜ FTSE100 ๋“ฑ ์ฃผ๊ฐ€์—ฐ๊ณ„์ฆ๊ถŒ(equity linked securities; ELS)์˜ ๊ธฐ์ดˆ์ž์‚ฐ์œผ๋กœ ์ฃผ๋กœ์‚ฌ์šฉํ•˜๋Š” ๋Œ€ํ‘œ์ ์ธ ํ•ด์™ธ ์ฃผ๊ฐ€์ง€์ˆ˜๋ฅผ ์ด์šฉํ•œ๋‹ค. 2010๋…„ 1์›”๋ถ€ํ„ฐ 2019๋…„ 12์›”๊นŒ์ง€ ์ด 10๋…„ ๋™์•ˆ์˜ ๋ฐ์ดํ„ฐ๋ฅผ์ด์šฉํ•˜์—ฌ์ถ”์ •ํ•œ๋ชจํ˜•์ด์‹ค์ œ๋ฐ์ดํ„ฐ์˜ˆ์ธก์—์–ผ๋งˆ๋‚˜์ •ํ™•ํ•˜๊ฒŒ์ ์šฉ๋ ์ˆ˜์žˆ๋Š”์ง€์•Œ์•„๋ณด๋ ค๊ณ ํ•œ๋‹ค.๋˜ํ•œ,์ธ๊ณต์ง€๋Šฅ๋ถ„์•ผ์˜๋ฐœ์ „์œผ๋กœ์ธํ•ด์ฃผ์‹๊ฐ€๊ฒฉ์˜ˆ์ธก์—๋„๋ฆฌ์‚ฌ์šฉ๋˜๊ณ ์žˆ๋Š”์„œํฌํŠธ๋ฒกํ„ฐํšŒ๊ท€(support vector regression;SVR)๋ฐฉ๋ฒ• (Cao์™€ Tay, 2001)์„๋น„๊ต๊ตฐ์œผ๋กœ์‚ฌ์šฉํ•˜์—ฌ๊ทธ๊ฒฐ๊ณผ๋ฅผ๋น„๊ตํ•˜๊ณ ์žํ•œ๋‹ค.๋ณธ๋…ผ๋ฌธ์˜๊ตฌ์„ฑ์€๋‹ค์Œ๊ณผ๊ฐ™๋‹ค. 2์žฅ์—์„œ๋Š” ์€๋‹‰ ๋งˆ๋ฅด์ฝ”ํ”„ ๋ชจ๋ธ ์ด๋ก ๊ณผ ๊ด€๋ จ๋œ ์ฃผ์š” ๋ฌธ์ œ๋“ค์— ๋Œ€ํ•ด ์†Œ๊ฐœํ•œ๋‹ค. 3์žฅ์—์„œ๋Š” ๊ตญ๋‚ด ๋ฐ ํ•ด์™ธ์ฃผ๊ฐ€์ง€์ˆ˜ ๋ฐ์ดํ„ฐ๋ฅผ ์ด์šฉํ•œ ์˜ˆ์ธก ๋ฐฉ๋ฒ•๊ณผ ๊ฒฐ๊ณผ๋ฅผ ์ œ์‹œํ•˜๋ฉฐ 4์žฅ์—์„œ๋Š” ๋ณธ ๋…ผ๋ฌธ์˜ ๊ฒฐ๋ก ๊ณผ ํ›„์† ์—ฐ๊ตฌ์˜ ๋ฐฉํ–ฅ์„์–ธ๊ธ‰ํ•˜๋ฉฐ๋งˆ๋ฌด๋ฆฌํ•œ๋‹ค.

2.์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ(Hidden Markov model)

2.1.์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ์†Œ๊ฐœ

์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ(hidden Markov model; HMM)์€๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ์˜ํ•˜๋‚˜๋กœ,์€๋‹‰๋œ์ƒํƒœ์™€๊ด€์ฐฐ๊ฐ€๋Šฅํ•œ๊ฒฐ๊ณผ์˜๋‘๊ฐ€์ง€์š”์†Œ๋กœ๊ตฌ์„ฑ๋œํ†ต๊ณ„์ ๋ชจ๋ธ์ด๋‹ค.์€๋‹‰์ƒํƒœ๋“ค์€๋งˆ๋ฅด์ฝ”ํ”„๊ณผ์ •์„๋”ฐ๋ฅด๊ณ ์ด๋ฅผ์ง์ ‘์ ์ธ์›์ธ์œผ๋กœํ•˜์—ฌ๊ด€์ฐฐ๊ฐ€๋Šฅํ•œ๊ฒฐ๊ณผ๊ฐ€๋ฐœ์ƒํ•œ๋‹ค.์ƒํƒœ๋ฅผ์ง์ ‘์ ์œผ๋กœ๋ณผ์ˆ˜์—†๊ณ ์ด๋กœ๋ถ€ํ„ฐ์•ผ๊ธฐ๋œ๊ฒฐ๊ณผ๋“ค๋งŒ๊ด€์ฐฐํ• ์ˆ˜์žˆ์–ดโ€˜์€๋‹‰(hidden)โ€™์ด๋ผ๋Š”๋‹จ์–ด๊ฐ€๋ถ™๊ฒŒ๋˜์—ˆ๋‹ค.๋ฐฉ๋ฒ•๋ก ์€ 1960๋…„๋Œ€์—์•Œ๋ ค์กŒ์ง€๋งŒ, 1970๋…„๋Œ€์—๋ชจ๋ธ์˜ํŒŒ๋ผ๋ฏธํ„ฐ์ถ”์ •์„์œ„ํ•œ๋ฐฉ๋ฒ•๋“ค์ด์—ฐ๊ตฌ๋˜๋ฉด์„œ์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ์—๋Œ€ํ•œ์—ฐ๊ตฌ๊ฐ€๋”์šฑํ™œ๋ฐœํžˆ์ง„ํ–‰๋˜์—ˆ๋‹ค (Baum๊ณผ Petrie,1966; Baum๋“ฑ, 1970).์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ์€ 1970๋…„๋Œ€์Œ์„ฑ์ธ์‹๋ถ„์•ผ์—์„œ์‘์šฉ๋˜๊ธฐ์‹œ์ž‘ํ•˜์—ฌ,์ƒ๋ฌผ์ •๋ณดํ•™,์ƒํƒœํ•™, ์–ธ์–ดํ•™, ํ™˜๊ฒฝ, ํ†ต์‹  ๋ฐ ๊ธˆ์œต ๋“ฑ ๋‹ค์–‘ํ•œ ๋ถ„์•ผ์—์„œ ์‚ฌ์šฉ๋˜๊ณ  ์žˆ๋‹ค (Cappe ๋“ฑ, 2006; Zucchini ๋“ฑ, 2017).ํŠนํžˆ ์€๋‹‰ ๋งˆ๋ฅด์ฝ”ํ”„ ๋ชจ๋ธ์€ ๊ด€์ฐฐ ๊ฐ€๋Šฅํ•œ ํ™•๋ฅ  ๊ณผ์ •์˜ ๊ฒฝ์šฐ ๋งˆ๋ฅด์ฝ”ํ”„ ์—ฐ์‡„๊ฐ€ ์ฃผ์–ด์ง„ ์ƒํ™ฉ์—์„œ ์กฐ๊ฑด๋ถ€ ๋…๋ฆฝ์ด

๋ฉฐ,๊ฐ์‹œ์ ์˜์กฐ๊ฑด๋ถ€๋ถ„ํฌ๋Š”์˜ค์งํ•ด๋‹น์‹œ์ ์˜๋งˆ๋ฅด์ฝ”ํ”„์—ฐ์‡„์—๋งŒ์˜์กดํ•˜๋Š”๊ธฐ๋ณธ๊ตฌ์กฐ๋ฅผ๊ฐ€์ง€๊ณ ์žˆ๋Š”๋ฐ,์ด๋Š”์ฃผ๊ฐ€์ง€์ˆ˜์›€์ง์ž„์—์ ํ•ฉํ•œ๊ตฌ์กฐ๋ผ๊ณ ํ• ์ˆ˜์žˆ๋‹ค.์ž„์˜์˜์‹œ์ ์˜์ฃผ๊ฐ€์ง€์ˆ˜๊ฐ€์€๋‹‰๋œ์—ฌ๋Ÿฌ์ƒํƒœ์—์˜ํ•ด์˜ํ–ฅ์„๋ฐ›์œผ๋ฉฐ๋งˆ๋ฅด์ฝ”ํ”„๊ณผ์ •์„๋”ฐ๋ฅธ๋‹ค๊ณ ๊ฐ€์ •์„ํ• ์ˆ˜์žˆ๊ธฐ๋•Œ๋ฌธ์ด๋‹ค.๋”ฐ๋ผ์„œ์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ์€์ฃผ๊ฐ€์ง€์ˆ˜์ž๋ฃŒ๋ถ„์„์—๋งŽ์ด์‘์šฉ๋˜๊ณ ์žˆ๋‹ค (Zucchini๋“ฑ, 2017).

์€๋‹‰ ๋งˆ๋ฅด์ฝ”ํ”„ ๋ชจ๋ธ์˜ ๊ตฌ์กฐ์™€ ์ด๋ฅผ ๋‚˜ํƒ€๋‚ด๋Š” ๊ตฌ์„ฑ ์š”์†Œ๋“ค์€ Figure 1๊ณผ Table 1์— ๊ฐ๊ฐ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ๋ณธ๋…ผ๋ฌธ์—์„œ๋Š” Idvall๊ณผ Jonsson (2008)๊ณผ Nguyen (2018)์—๋‚˜์™€์žˆ๋Š”๊ธฐํ˜ธ๋ฅผ์ฐธ๊ณ ํ•˜์—ฌ์‚ฌ์šฉํ•˜์˜€๋‹ค.๊ด€์ธก๋˜์ง€์•Š๋Š”๋งˆ๋ฅด์ฝ”ํ”„์—ฐ์‡„ Q๋Š”์ „์ดํ™•๋ฅ ํ–‰๋ ฌ A์™€์ดˆ๊ธฐํ™•๋ฅ  p๋ฅผ๊ฐ€์ง„๋‹ค.๊ด€์ฐฐ๊ฐ€๋Šฅํ•œํ™•๋ฅ ๊ณผ์ • O๋Š”๋งˆ๋ฅด์ฝ”ํ”„์—ฐ์‡„๊ฐ€์ฃผ์–ด์ง„์ƒํ™ฉ์—์„œ์กฐ๊ฑด๋ถ€๋…๋ฆฝ์ด๋ฉฐ,๊ฐ์‹œ์ ์˜์กฐ๊ฑด๋ถ€๋ถ„ํฌ๋Š”์˜ค์งํ•ด๋‹น์‹œ์ ์˜๋งˆ๋ฅด์ฝ”ํ”„์—ฐ์‡„์—๋งŒ์˜์กดํ•œ๋‹ค.

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A hidden Markov model for predicting global stock market index 463

Figure 1: Illustration of hidden Markov model.

Table 1: Basic elements of HMM

Element Definition/NotationLength of observation data TNumber of states NNumber of symbols MObservation sequence O = {Ot , t = 1, 2, . . . ,T }Hidden states sequence Q = {qt , t = 1, 2, . . . ,T }Possible values of states {S i, i = 1, 2, . . . ,N}Possible symbols {vk , k = 1, 2, . . . ,M}Initial probability p = (pi), pi = P(q1 = S i), i = 1, 2, . . . ,NTransition probability matrix A = (ai j), ai j = P(qt = S j |qtโˆ’1 = S i), i, j = 1, 2, . . . ,NEmission probability matrix B = (bik), bik = P(Ot = vk |qt = S i), i = 1, . . . ,N, k = 1, . . . ,M

์ด๋ฅผ์ˆ˜์‹์œผ๋กœํ‘œํ˜„ํ•˜๋ฉด๋‹ค์Œ๊ณผ๊ฐ™๋‹ค.

P(qt |q1, q2, . . . , qtโˆ’1) = P(qt |qtโˆ’1), t = 2, 3, . . . ,

P(Ot |O1, . . . ,Otโˆ’1, q1, . . . , qt) = P(Ot |qt), t = 1, 2, 3 . . . .

๋งˆ์ฝ”๋ฅดํ”„ ์—ฐ์‡„๊ฐ€ ์ฃผ์–ด์กŒ์„ ๋•Œ ๊ด€์ฐฐ ๊ฐ€๋Šฅํ•œ ํ™•๋ฅ ๊ณผ์ •์ด์ด์‚ฐํ˜• ๋ถ„ํฌ๋ผ๋ฉด ์ด์‚ฐํ˜• HMM์ด๊ณ , ์—ฐ์†ํ˜• ๋ถ„ํฌ๋ผ๋ฉด ์—ฐ์†ํ˜• HMM์ด ๋œ๋‹ค. Table 1์„ ์ฐธ๊ณ ํ•˜๋ฉด, HMM๋ฅผ ๋‚˜ํƒ€๋‚ด๊ธฐ ์œ„ํ•ด์„œ ํ•„์š”ํ•œ ํŒŒ๋ผ๋ฏธํ„ฐ๋Š” ฮป โ‰ก {A, B, p}์ž„์„์•Œ์ˆ˜์žˆ๋‹ค.์˜ˆ๋ฅผ๋“ค์–ด,์—ฐ์†ํ˜• HMM์—์„œ๊ฐ€์šฐ์‹œ์•ˆ๋ถ„ํฌ๋ฅผ๊ฐ€์ •ํ•œ๋‹ค๋ฉด,ํŒŒ๋ผ๋ฏธํ„ฐ๋Š”๋‹ค์Œ๊ณผ๊ฐ™์ด๋‚˜ํƒ€๋‚ผ์ˆ˜์žˆ๋‹ค.

ฮป โ‰ก {A, B, p} โ‰ก {A, ยต, ฯƒ, p}.

2.2.์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ์˜์ฃผ์š”๋ฌธ์ œ

HMM์„์‹ค์ œ๋กœํ™œ์šฉํ•˜๊ธฐ์œ„ํ•ด์„œ๋Š”์šฐ์„  3๊ฐ€์ง€์ฃผ์š”๋ฌธ์ œ์—๋Œ€ํ•ด์ƒ๊ฐํ•ด๋ณด์•„์•ผํ•œ๋‹ค (Rabiner, 1989).์ฒซ๋ฒˆ์งธ๋ฌธ์ œ๋Š”๊ด€์ฐฐ๊ฐ€๋Šฅํ•œ์ˆ˜์—ด {Ot}์™€๋ชจ๋ธ์˜ํŒŒ๋ผ๋ฏธํ„ฐ ฮป โ‰ก {A, B, p}๊ฐ€์ฃผ์–ด์กŒ์„๋•Œ,์ฃผ์–ด์ง„๋ชจ๋ธ์—์„œ๊ด€์ธก์ˆ˜์—ด์˜ํ™•๋ฅ ์„ ๊ณ„์‚ฐํ•˜๋Š” ํ‰๊ฐ€ ๋ฌธ์ œ์ด๋‹ค. ๊ฐ™์€ ์ƒํ™ฉ์—์„œ ๊ด€์ธก ์ˆ˜์—ด์„ ๋‚˜ํƒ€๋‚ผ ํ™•๋ฅ ์ด ๊ฐ€์žฅ ํฐ ์€๋‹‰ ์ƒํƒœ ์ˆ˜์—ด์„ ์ฐพ๋Š”

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464 Hajin Kang, Beom Seuk Hwang

ํ•ด๋… ๋ฌธ์ œ, ๊ทธ๋ฆฌ๊ณ  ๊ด€์ธก ์ˆ˜์—ด๋งŒ ์ฃผ์–ด์ง„ ๊ฒฝ์šฐ ์ด๋ฅผ ๊ฐ€์žฅ ์ž˜ ๋‚˜ํƒ€๋‚ด๋Š” ๋ชจ๋ธ ํŒŒ๋ผ๋ฏธํ„ฐ๋ฅผ ์ฐพ๋Š” ํ•™์Šต ์ถ”์ • ๋ฌธ์ œ๊ฐ€๋‚˜๋จธ์ง€์ฃผ์š”๋ฌธ์ œ์ด๋‹ค.

(i) ํ‰๊ฐ€๋ฌธ์ œ(evaluation question)

(a) ๊ด€์ฐฐ ๊ฐ€๋Šฅํ•œ ์ˆ˜์—ด O = {Ot, t = 1, 2, . . . ,T }์™€ ๋ชจ๋ธ์˜ ํŒŒ๋ผ๋ฏธํ„ฐ ฮป โ‰ก {A, B, p}๊ฐ€ ์ฃผ์–ด์กŒ์„ ๋•Œ, ๊ด€์ธก์ˆ˜์—ด์˜ํ™•๋ฅ  P(O|ฮป)๋ฅผ๊ณ„์‚ฐํ•œ๋‹ค.

(ii) ํ•ด๋…๋ฌธ์ œ(decoding question)

(a) ๊ด€์ฐฐ ๊ฐ€๋Šฅํ•œ ์ˆ˜์—ด O = {Ot, t = 1, 2, . . . ,T }์™€ ๋ชจ๋ธ์˜ ํŒŒ๋ผ๋ฏธํ„ฐ ฮป โ‰ก {A, B, p}๊ฐ€ ์ฃผ์–ด์กŒ์„ ๋•Œ, ๊ด€์ธก์ˆ˜์—ด์„๋‚˜ํƒ€๋‚ด๋Š”๋ฐ๊ฐ€์žฅ์ ํ•ฉํ•œ์€๋‹‰์ƒํƒœ์ˆ˜์—ด์„ํ™•์ธํ•œ๋‹ค. argmaxQP(Q|O, ฮป)๋ฅผ๊ณ„์‚ฐํ•œ๋‹ค.

(iii) ํ•™์Šต์ถ”์ •๋ฌธ์ œ(learning question)

(a) ๊ด€์ฐฐ๊ฐ€๋Šฅํ•œ์ˆ˜์—ดO = {Ot, t = 1, 2, . . . ,T }๋งŒ์ฃผ์–ด์ง„๊ฒฝ์šฐ,์ด๋ฅผ๊ฐ€์žฅ์ž˜๋‚˜ํƒ€๋‚ด๋Š”HMM์˜ํŒŒ๋ผ๋ฏธํ„ฐฮป๊ฐ€๋ฌด์—‡์ธ์ง€ํ™•์ธํ•œ๋‹ค. argmaxฮปP(O|ฮป)๋ฅผ๊ณ„์‚ฐํ•œ๋‹ค.

ํ‰๊ฐ€ ๋ฌธ์ œ๋Š” ํ™•๋ฅ ์˜ ์ถ”์ • ๋ฌธ์ œ์™€ ๊ฐ™์œผ๋ฉฐ, ์ง์ ‘์ ์ธ ๋ฐฉ๋ฒ•์„ ์‚ฌ์šฉํ•œ ๊ณ„์‚ฐ๋ณด๋‹ค๋Š” ์ „ํ–ฅ(forward) ๋˜๋Š” ํ›„ํ–ฅ ์•Œ๊ณ ๋ฆฌ์ฆ˜(backward algorithm)์„์ด์šฉํ•˜์—ฌ๋ฌธ์ œ๋ฅผํ•ด๊ฒฐํ•œ๋‹ค.ํ•ด๋…๋ฌธ์ œ๋Š”์ตœ์ ์˜์ƒํƒœ์ˆ˜์—ด์„์ฐพ๋Š”๋ฌธ์ œ์™€๊ฐ™์œผ๋ฉฐ๋น„ํ„ฐ๋น„ ์•Œ๊ณ ๋ฆฌ์ฆ˜(Viterbi algorithm)์„ ์ด์šฉํ•œ๋‹ค (Viterbi, 1967). ๋งˆ์ง€๋ง‰์œผ๋กœ ํ•™์Šต ์ถ”์ • ๋ฌธ์ œ๋Š” ๋ชจ์ˆ˜ ์ถ”์ • ๋ฐ์žฌ์ถ”์ •์˜๋ฌธ์ œ์™€๊ฐ™์œผ๋ฉฐ,์ตœ์ ์˜๋ชจ๋ธ๋กœ๊ฐœ์„ ํ•˜๊ธฐ์œ„ํ•ด์„œ๋ฐ˜๋ณต์ ์ธํ•ด๋ฒ•์„ํ•„์š”๋กœํ•œ๋‹ค. EM์•Œ๊ณ ๋ฆฌ์ฆ˜์˜ํ•˜๋‚˜์ธ๋ฐ”์›€-์›ฐ์น˜์•Œ๊ณ ๋ฆฌ์ฆ˜(Baum-Welch algorithm)์€๊ตญ์†Œ์ตœ์šฐ์ถ”์ •์น˜๋กœ์„œ์ˆ˜๋ ด์ด์ž˜๋˜๊ธฐ๋•Œ๋ฌธ์— HMM์—์„œ์˜ํ•™์Šต ์ถ”์ • ๋ฌธ์ œ๋ฅผ ํ•ด๊ฒฐํ•˜๊ธฐ ์œ„ํ•ด ์ผ๋ฐ˜์ ์œผ๋กœ ์‚ฌ์šฉ๋œ๋‹ค (Welch, 2003). ์—ฌ๊ธฐ์„œ๋Š” ๋ฐ”์›€-์›ฐ์น˜ ์•Œ๊ณ ๋ฆฌ์ฆ˜์— ๋Œ€ํ•ด๊ฐ„๋žตํžˆ์†Œ๊ฐœํ•œ๋‹ค.๋จผ์ €์•Œ๊ณ ๋ฆฌ์ฆ˜์„์ดํ•ดํ•˜๋Š”๋ฐํ•„์š”ํ•œํ™•๋ฅ  ฮฑ, ฮฒ๋ฅผ๋‹ค์Œ๊ณผ๊ฐ™์ด์ •์˜ํ•œ๋‹ค.

ฮฑ(l)t (i) = P

(O(l)

1 ,O(l)2 , . . . ,O

(l)t , qt = S i|ฮป

), t = 1, 2, . . . ,T and l = 1, 2, . . . , L,

ฮฒ(l)t (i) = P

(O(l)

t+1,O(l)t+2, . . . ,O

(l)T | qt = S i, ฮป

), t = 1, 2, . . . ,T and l = 1, 2, . . . , L.

ฮฑ(l)t (i)๋Š” l๋ฒˆ์งธ ์ƒ˜ํ”Œ์— ๋Œ€ํ•ด ๋ชจ๋ธ์˜ ํŒŒ๋ผ๋ฏธํ„ฐ ฮป๊ฐ€ ์ฃผ์–ด์กŒ์„ ๋•Œ, t์‹œ์ ์˜ ์ƒํƒœ๊ฐ€ S i์ด๋ฉด์„œ t์‹œ์ ๊นŒ์ง€์˜ ๊ด€์ธก๋œ๋ฐ์ดํ„ฐ๊ฐ€ ๋‚˜ํƒ€๋‚  ํ™•๋ฅ ์„ ์˜๋ฏธํ•˜๊ณ , ฮฒ(l)

t (i)๋Š” t์‹œ์ ์˜ ์ƒํƒœ๊ฐ€ S i๋กœ ์ฃผ์–ด์กŒ์„ ๋•Œ, t์‹œ์  ์ดํ›„์˜ ๋ฐ์ดํ„ฐ๊ฐ€ ๋‚˜ํƒ€๋‚ ํ™•๋ฅ ์„์˜๋ฏธํ•œ๋‹ค.๋˜ํ•œ,๋ชจ๋ธ์˜ํŒŒ๋ผ๋ฏธํ„ฐ์™€๊ด€์ธก์ˆ˜์—ด์ด์ฃผ์–ด์กŒ์„๋•Œ, t์‹œ์ ์˜์ƒํƒœ๊ฐ€ S i์ผํ™•๋ฅ  ฮณ(l)

t (i)์€๋‹ค์Œ๊ณผ๊ฐ™์ด์ •์˜ํ•œ๋‹ค.

ฮณ(l)t (i) = P

(qt = S i|O(l), ฮป

)=ฮฑ(l)

t (i)ฮฒ(l)t (i)

P(O(l)|ฮป)=

ฮฑ(l)t (i)ฮฒ(l)

t (i)โˆ‘Nk=1 ฮฑ

(l)t (k)ฮฒ(l)

t (k).

t์‹œ์ ์˜ ์ƒํƒœ๊ฐ€ S i์ด๊ณ  t + 1์‹œ์ ์˜ ์ƒํƒœ๊ฐ€ S j์ผ ํ™•๋ฅ  ฮพ(l)t (i, j)์€ ๋‹ค์Œ๊ณผ ๊ฐ™์ด ๋‚˜ํƒ€๋‚ผ ์ˆ˜ ์žˆ๊ณ , ์ด๋•Œ ฮณ(l)

t (i)์™€์˜๊ด€๊ณ„๋˜ํ•œ๋‹ค์Œ๊ณผ๊ฐ™์ดํ‘œํ˜„ํ• ์ˆ˜์žˆ๋‹ค.

ฮพ(l)t (i, j) = P

(qt = S i, qt+1 = S j| O(l), ฮป

)=ฮฑ(l)

t (i)ai jb j(O(l)t+1)ฮฒ(l)

t+1( j)P(O(l)|ฮป)

,

ฮณ(l)t (i) =

Nโˆ‘j=1

ฮพ(l)t (i, j).

๋ฐ”์›€-์›ฐ์น˜์•Œ๊ณ ๋ฆฌ์ฆ˜์˜๊ณผ์ •์€๋‹ค์Œ๊ณผ๊ฐ™์ด๋‚˜ํƒ€๋‚ผ์ˆ˜์žˆ๋‹ค.

Page 5: A hidden Markov model for predicting global stock market index

A hidden Markov model for predicting global stock market index 465

Algorithm 1 Baum-Welch algorithm

1: ๊ธธ์ด๊ฐ€ T์ธ L๊ฐœ์˜๋…๋ฆฝ๊ด€์ธก์ˆ˜์—ด O = (O(1),O(2), . . . ,O(L))์„๊ณ ๋ คํ•œ๋‹ค.2: (ฮป, ฮด,โˆ†)์—๋Œ€ํ•œ์ดˆ๊ธฐ๊ฐ’์„์„ค์ •ํ•œ๋‹ค.3: ๋‹ค์Œ์กฐ๊ฑด์„๋งŒ์กฑํ• ๋•Œ๊นŒ์ง€์•„๋ž˜๊ณผ์ •์„๋ฐ˜๋ณตํ•œ๋‹ค.์ด๋•Œ, โˆ† < ฮด.

(a) ์ „ํ–ฅ์•Œ๊ณ ๋ฆฌ์ฆ˜์„์ด์šฉํ•ด๋‹ค์Œ์„๊ณ„์‚ฐํ•œ๋‹ค.

P(O, ฮป) =

Lโˆl=1

P(O(l)|ฮป

),

(b) 1 โ‰ค i โ‰ค N์—๋Œ€ํ•ด์„œ์ƒˆ๋กœ์šดํŒŒ๋ผ๋ฏธํ„ฐ ฮปโˆ— = {Aโˆ—, Bโˆ—, pโˆ—}๋ฅผ๊ณ„์‚ฐํ•œ๋‹ค.

pโˆ—i =1L

Lโˆ‘l=1

ฮณ(l)1 (i),

aโˆ—i j =

โˆ‘Ll=1

โˆ‘Tโˆ’1t=1 ฮพ

(l)t (i, j)โˆ‘L

l=1โˆ‘Tโˆ’1

t=1 ฮณ(l)t (i)

, 1 โ‰ค j โ‰ค N,

bโˆ—i (k) =

โˆ‘Ll=1

โˆ‘Tโˆ’1t=1 I(O(l)

t = v(l)k )ฮณ(l)

t (i)โˆ‘Ll=1

โˆ‘Tโˆ’1t=1 ฮณ

(l)t (i)

, 1 โ‰ค k โ‰ค M.

(c) โˆ† = P(O, ฮปโˆ—) โˆ’ P(O, ฮป)๋ฅผ๊ณ„์‚ฐํ•œ๋‹ค.

(d) ๋‹ค์Œ์„์—…๋ฐ์ดํŠธํ•œ๋‹ค.

ฮป = ฮปโˆ—.

4: ํŒŒ๋ผ๋ฏธํ„ฐ๊ฒฐ๊ณผ๋ฅผํ™•์ธํ• ์ˆ˜์žˆ๋‹ค.

2.3.๋‹ค๋ณ€๋Ÿ‰ Gaussian์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ

์ฃผ๊ฐ€์ง€์ˆ˜ ๋ฐ์ดํ„ฐ๋Š” ์ข…๊ฐ€, ์‹œ๊ฐ€, ๊ณ ๊ฐ€, ์ €๊ฐ€๋ฅผ ํฌํ•จํ•˜๊ณ  ์žˆ๋‹ค. 4๊ฐœ์˜ ๊ด€์ฐฐ ๊ฐ€๋Šฅํ•œ ๋ฐ์ดํ„ฐ๋ฅผ ์ด์šฉํ•˜์—ฌ ์€๋‹‰ ๋งˆ๋ฅด์ฝ”ํ”„ ๋ชจ๋ธ(HMM)์— ์ ์šฉํ•  ๋•Œ ๊ด€์ฐฐ ๊ฐ€๋Šฅํ•œ ๋ฐ์ดํ„ฐ๊ฐ€ ์—ฐ์†ํ˜• ๋ณ€์ˆ˜์ด๋ฏ€๋กœ ๊ฐ€์žฅ ๊ธฐ๋ณธ์ด ๋˜๋Š” ๋ชจํ˜•์ธ ๋‹ค๋ณ€๋Ÿ‰(multivariate) Gaussian์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ์„๊ณ ๋ คํ•ด๋ณผ์ˆ˜์žˆ๋‹ค.๋‹ค๋ณ€๋Ÿ‰ Gaussian์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ์€๊ด€์ฐฐ๊ฐ€๋Šฅํ•œ ๋ฐ์ดํ„ฐ์˜ ํ™•๋ฅ ๋ถ„ํฌ๊ฐ€ ์ •๊ทœ๋ถ„ํฌ๋ฅผ ๋”ฐ๋ฅด๋Š” ์œ ํ•œ ์ƒํƒœ๊ณต๊ฐ„(finite state space)์ด๋ฉด์„œ ๋™์งˆ์ ์ธ(homoge-neous) ์€๋‹‰ ๋งˆ๋ฅด์ฝ”ํ”„ ๋ชจ๋ธ์˜ ํ˜•ํƒœ๋ฅผ ๋ ๊ณ  ์žˆ๋‹ค. ๋งˆ๋ฅด์ฝ”ํ”„ ์—ฐ์‡„ ์ƒํƒœ๊ฐ€ qt = S i๋กœ ์ฃผ์–ด์ง„ ๊ฒฝ์šฐ ๊ด€์ธก์น˜ Ot์˜

์กฐ๊ฑด๋ถ€๋ถ„ํฌ๋Š”ํ˜ผํ•ฉ๊ฐ€์šฐ์‹œ์•ˆ๋ถ„ํฌ๋ฅผ๋‚˜ํƒ€๋‚ด๋ฉฐํ™•๋ฅ ๋ฐ€๋„ํ•จ์ˆ˜๋Š”๋‹ค์Œ๊ณผ๊ฐ™๋‹ค.

bi(Ot) =

Mโˆ‘k=1

wikbik(Ot) =

Mโˆ‘k=1

wikN(Ot; ยตik,ฮฃik), i = 1, 2, . . . ,N.

์ด๋•Œ, wik๋Š”์ƒํƒœ๊ฐ€ S i์ผ๋•Œ k๋ฒˆ์งธํ˜ผํ•ฉ๊ทธ๋ฃน์—๋Œ€ํ•œ๊ฐ€์ค‘์น˜๋ฅผ๋‚˜ํƒ€๋‚ด๋ฉฐ wik โ‰ฅ 0๊ณผ wi1 + wi2 + ยท ยท ยท + wiM = 1๋ฅผ๋งŒ์กฑํ•œ๋‹ค.๊ทธ๋ฆฌ๊ณ , ยตik,ฮฃik๋Š”๊ฐ๊ฐ i๋ฒˆ์งธ์ƒํƒœ์˜ k๋ฒˆ์งธํ˜ผํ•ฉ๊ทธ๋ฃน์˜ํ‰๊ท ๊ณผ๊ณต๋ถ„์‚ฐํ–‰๋ ฌ์„๋‚˜ํƒ€๋‚ธ๋‹ค.์ฆ‰,๋‹ค๋ณ€๋Ÿ‰Gaussian์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ์„๊ตฌ์„ฑํ•˜๋Š”ํŒŒ๋ผ๋ฏธํ„ฐ๋Š”์ „์ดํ™•๋ฅ ํ–‰๋ ฌ A์™€์ดˆ๊ธฐํ™•๋ฅ  p,ํ‰๊ท  ยต,๊ณต๋ถ„์‚ฐํ–‰๋ ฌ ฮฃ๋กœ

๊ตฌ์„ฑ๋œ ฮป = (A, ยต,ฮฃ, p)์ด๋‹ค.

Page 6: A hidden Markov model for predicting global stock market index

466 Hajin Kang, Beom Seuk Hwang

Figure 2: Daily changes in KOSPI200 closing price.

3.์‹ค์ œ๋ฐ์ดํ„ฐ๋ถ„์„

3.1.์ฃผ๊ฐ€์ง€์ˆ˜๋ฐ์ดํ„ฐ

์ฃผ๊ฐ€์ง€์ˆ˜๋ž€๊ฑฐ๋ž˜์†Œ์—์ƒ์žฅ๋ฐ๋“ฑ๋ก๋œ์ฃผ์‹์˜์‹œ์žฅ๊ฐ€๊ฒฉ์„ํ† ๋Œ€๋กœํ˜•์„ฑ๋˜์–ด์ „๋ฐ˜์ ์ธ์ฃผ๊ฐ€์˜๋™ํ–ฅ์„๋‚˜ํƒ€๋‚ด๋Š”

๋Œ€ํ‘œ์ ์ธ์ง€์ˆ˜๋กœ๊ฐ๋‚˜๋ผ์˜๋ฒค์น˜๋งˆํฌ์ง€์ˆ˜๋กœ์‚ฌ์šฉ๋œ๋‹ค.๋‚˜๋ผ๋งˆ๋‹ค์‹œ์žฅ์„๋Œ€ํ‘œํ•˜๋Š”์ฃผ๊ฐ€์ง€์ˆ˜๋Š”๋‹ค์–‘ํ•˜์ง€๋งŒ,๋ณธ๋…ผ๋ฌธ์—์„œ๋Š” ์ฃผ๊ฐ€์—ฐ๊ณ„์ฆ๊ถŒ(equity linked securities; ELS)์—์„œ ์ฃผ๋กœ ์‚ฌ์šฉ๋˜๋Š” ๊ธฐ์ดˆ์ž์‚ฐ์„ ๋ฐ”ํƒ•์œผ๋กœ ๋‹ค์„ฏ ๊ฐœ์˜๊ตญ๊ฐ€๋ณ„ ์ฃผ๊ฐ€์ง€์ˆ˜๋ฅผ ์„ ํƒํ•˜์˜€๋‹ค. ํ•œ๊ตญ์˜ KOSPI200 ์ง€์ˆ˜, ์ผ๋ณธ์˜ NIKKEI225 ์ง€์ˆ˜, ํ™์ฝฉ์˜ HSI ์ง€์ˆ˜, ๋ฏธ๊ตญ์˜S&P500์ง€์ˆ˜,์˜๊ตญ์˜ FTSE100์ง€์ˆ˜์ด๋‹ค.๋ฐ์ดํ„ฐ๋Š” 2010๋…„ 1์›”๋ถ€ํ„ฐ 2019๋…„ 12์›”๋ง๊นŒ์ง€์ด 10๋…„๋™์•ˆ์˜์ผ๋ณ„์ฃผ๊ฐ€์ง€์ˆ˜๋ฐ์ดํ„ฐ์ด๋ฉฐ,์ถœ์ฒ˜๋Š”์•ผํ›„ํŒŒ์ด๋‚ธ์Šค(finance.yahoo.com)์™€ํ•œ๊ตญ๊ฑฐ๋ž˜์†Œ(krx.co.kr)์ด๋‹ค.

Figure 2์€ ๊ตญ๋‚ด KOSPI200 ๋ฐ์ดํ„ฐ์˜ ์ผ๋ณ„ ๋ณ€ํ™” ์ถ”์ด๋ฅผ ๋‚˜ํƒ€๋‚ด๋ฉฐ, ํ•ด์™ธ ์ฃผ๊ฐ€์ง€์ˆ˜๋“ค์˜ ๋ฐ์ดํ„ฐ ๊ทธ๋ž˜ํ”„๋Š”Figure 3๋ฅผ ํ†ตํ•ด ํ™•์ธํ•  ์ˆ˜ ์žˆ๋‹ค. ๊ตญ๋‚ด KOSPI200 ๊ทธ๋ž˜ํ”„์™€ ํ•ด์™ธ ์ฃผ๊ฐ€์ง€์ˆ˜๋“ค์˜ ๊ทธ๋ž˜ํ”„๋ฅผ ์‚ดํŽด๋ณด๋ฉด, 2010๋…„๋ถ€ํ„ฐ 2019๋…„๊นŒ์ง€ 10๋…„ ๋™์•ˆ ์ „๋ฐ˜์ ์œผ๋กœ ์ƒ์Šนํ•˜๋Š” ์ถ”์„ธ๊ฐ€ ์žˆ์Œ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ๊ฐ ๊ตญ๊ฐ€ ์ฃผ๊ฐ€์ง€์ˆ˜๋งˆ๋‹ค์ž์„ธํ•œ์ถ”์ด๋‚˜,์ „์ฒด์ ์ธํŒจํ„ด์€๋‹ค๋ฅธ์–‘์ƒ์„๋‚˜ํƒ€๋‚ธ๋‹ค.์•„์‹œ์•„๊ถŒ์ง€์ˆ˜๋“ค์ธ KOSPI200๊ณผ HSI์ง€์ˆ˜์˜๊ฒฝ์šฐ๊ทธ๋ž˜ํ”„์˜ํŒจํ„ด์€๋น„์Šทํ•ด๋ณด์ด๋‚˜NIKKEI225์ง€์ˆ˜์˜ํŒจํ„ด์€๋‘˜๊ณผ๋Š”๋‹ค๋ฅธํŒจํ„ด์„๋‚˜ํƒ€๋‚ธ๋‹ค.์˜๊ตญ์ง€์ˆ˜์ธ FTSE100์˜๊ฒฝ์šฐ์•„์‹œ์•„๊ถŒ์ง€์ˆ˜๋“ค๊ณผ๋Š”๋˜๋‹ค๋ฅธํŒจํ„ด์˜๋ชจ์Šต์„์ง€๋‚œ 10๋…„๊ฐ„๋ณด์—ฌ์™”์œผ๋ฉฐ์„ธ๊ณ„์ ์œผ๋กœ๊ธฐ์ค€์ง€์ˆ˜๊ฐ€๋˜๋Š”๋ฏธ๊ตญ์˜ S&P500์€์ง€์ˆ˜์˜์ „์ฒด์ ์ธ๋ณ€๋™ํญ์ด์•„์ฃผ์ž‘์•„์•ˆ์ •์ ์œผ๋กœ์›€์ง์ด๋Š”๊ฒƒ์—๋น„ํ•ด,๋‚˜๋จธ์ง€ 4๊ฐœ์ง€์ˆ˜์˜๊ฒฝ์šฐ์ƒ๋Œ€์ ์œผ๋กœํฐ๋ณ€๋™ํญ์œผ๋กœ์›€์ง์ด๊ณ ์žˆ์Œ์„์•Œ์ˆ˜์žˆ๋‹ค.

3.2.์ฃผ๊ฐ€์ง€์ˆ˜์˜ˆ์ธก๋ฐฉ๋ฒ•

์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ์€๊ฒฝ์ œ์ ์ƒํ™ฉ์˜ˆ์ธก์ด๋‚˜๋ณ€๋™์„ฑ,์ฃผ์‹์›€์ง์ž„์˜ˆ์ธก๋“ฑ๊ณผ๊ฐ™์ด๊ธˆ์œต๋ถ„์•ผ์—์„œ๋„๋ฆฌ์‚ฌ์šฉ๋˜๊ณ  ์žˆ๋‹ค (๋ฐ•ํ˜•์ค€ ๋“ฑ, 2007; Lee์™€ Oh, 2007; Nguyen, 2018). ๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” HMM์„ ์ด์šฉํ•ด ์„ธ๊ณ„ ์ฃผ๊ฐ€์ง€์ˆ˜๋ฅผ๋ถ„์„ํ•ด๋ณด๊ณ , ๊ฐ ๊ตญ๊ฐ€๋ณ„ ์ฃผ๊ฐ€์ง€์ˆ˜์˜ ์ถ”์ด์™€ ์›€์ง์ž„ ๊ทธ๋ฆฌ๊ณ  ๊ฐ€๊ฒฉ ๋“ฑ์„ ์˜ˆ์ธกํ•ด ๋ณด๊ณ ์ž ํ•œ๋‹ค. ํŠนํžˆ ๊ตญ๋‚ด ์‹œ์žฅ์˜๋ฒค์น˜๋งˆํฌ์ง€์ˆ˜๋กœ๊ฐ€์žฅ๋„๋ฆฌ์ด์šฉํ•˜๋Š” KOSPI200์ง€์ˆ˜๋ฅผ์ž์„ธํžˆ์‚ดํŽด๋ณด๊ณ ๋ชจ๋ธ์—์ ์šฉํ•˜๊ณ ์žํ•œ๋‹ค. 2010๋…„ 1์›”๋ถ€ํ„ฐ 2019๋…„ 12์›” ๋ง๊นŒ์ง€ ์ „์ฒด ๋ฐ์ดํ„ฐ ์ค‘์—์„œ ๋งˆ์ง€๋ง‰ 100 ์˜์—…์ผ์— ํ•ด๋‹นํ•˜๋Š” ๋ฐ์ดํ„ฐ๋ฅผ ์˜ˆ์ธกํ•˜๊ณ ์ž ํ•˜๋Š”๋ฐ์ดํ„ฐ๋กœ์จ์„ ํƒํ•˜์˜€๋‹ค.

HMM์„ ์ด์šฉํ•ด์„œ ์ฃผ๊ฐ€์ง€์ˆ˜๋ฅผ ์˜ˆ์ธกํ•˜๋Š” ๊ณผ์ •์€ ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค. HMM ๋ชจ๋ธ์˜ ์„ฑ๊ณผ๋ฅผ ํ‰๊ฐ€ํ•˜๊ธฐ ์œ„ํ•ด AIC,

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A hidden Markov model for predicting global stock market index 467

Figure 3: Daily changes in NIKKEI225, HSI, S&P500 and FTSE100 closing prices.

BIC๋“ฑ๊ณผ๊ฐ™์€๊ธฐ์ค€์„๋„์ž…ํ•˜๊ณ ,์ด๋ฅผ๋ฐ”ํƒ•์œผ๋กœ๊ฐ๊ฐ์€๋‹‰์ƒํƒœ์˜์ˆ˜์—๋”ฐ๋ฅธ๋ชจ๋ธ์„๋น„๊ตํ•˜์—ฌ๋ฐ์ดํ„ฐ๋‚ด์—๋‚ด์žฌํ•˜๋Š” ์ตœ์ ์˜ ์ƒํƒœ์˜ ์ˆ˜๋ฅผ ์„ ํƒํ•œ๋‹ค. ์ถ”์ •๋œ ์ƒํƒœ์˜ ์ˆ˜๋ฅผ ๋ฐ”ํƒ•์œผ๋กœ ์€๋‹‰ ๋งˆ๋ฅด์ฝ”ํ”„ ๋ชจ๋ธ์„ ํ•™์Šตํ•˜๋Š” ๋ฐ์—๋Š”์ „์ฒด ๋ฐ์ดํ„ฐ๋ฅผ ํ•™์Šต ๋ฐ์ดํ„ฐ์™€ ์‹คํ—˜ ๋ฐ์ดํ„ฐ๋กœ ๋‚˜๋ˆ„์–ด ์ง„ํ–‰ํ•œ๋‹ค. ํ•™์Šต ๋ฐ์ดํ„ฐ๋ฅผ ์ด์šฉํ•ด ๊ตฌ์ถ•ํ•œ ๋ชจํ˜•์„ ์˜ˆ์ธก์—ํ™œ์šฉํ•˜๊ณ , ์‹คํ—˜ ๋ฐ์ดํ„ฐ์™€์˜ ์˜ˆ์ธก ์˜ค์ฐจ๋ฅผ ์ธก์ •ํ•˜์—ฌ ์˜ˆ์ธก ๋ชจ๋ธ์ด ์ตœ์ ์œผ๋กœ ์ƒ์„ฑ๋˜์—ˆ๋Š”์ง€ ๊ฒฐ๊ณผ๋ฅผ ํ™•์ธํ•œ๋‹ค. ๋ณธ๋…ผ๋ฌธ์—์„œ์‚ฌ์šฉ๋œ๋ชจ๋“ ๋ถ„์„์—๋Š” Python hmmlearnํŒจํ‚ค์ง€๋ฅผ์ด์šฉํ•˜์˜€๋‹ค (Lebedev๋“ฑ, 2017).

3.2.1.๋ชจ๋ธ์„ ํƒ:์ƒํƒœ์˜์ˆ˜๊ฒฐ์ •

์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ์—์„œ์€๋‹‰์ƒํƒœ์˜์ˆ˜๋ฅผ๊ฒฐ์ •ํ•˜๋Š”๊ฒƒ์€๊ต‰์žฅํžˆ์ค‘์š”ํ•˜๋‹ค.์€๋‹‰์ƒํƒœ์˜์ˆ˜๊ฐ€๋งŽ์„์ˆ˜๋ก๋ชจ๋ธ์ด๋”์ ์ ˆํ•œ๊ฒƒ์ฒ˜๋Ÿผ๋ณด์ผ์ˆ˜๋„์žˆ์œผ๋‚˜,์ด๋Ÿด๊ฒฝ์šฐ๋ชจ๋ธ์„๊ตฌ์ถ•ํ•˜๊ธฐ์œ„ํ•ด์ถ”์ •ํ•ด์•ผํ• ๋ชจ์ˆ˜์˜์ˆ˜๊ฐ€์ฆ๊ฐ€ํ•˜๋ฏ€๋กœ๊ฐ„๊ฒฐ์„ฑ์˜ ์›์น™์—์„œ ๋ฒ—์–ด๋‚˜๊ฑฐ๋‚˜ ๊ณ„์‚ฐ ๊ณผ์ •์ด ์˜ค๋ž˜ ๊ฑธ๋ฆฌ๋Š” ๋“ฑ ๋น„ํšจ์œจ์ ์ธ ๋ชจ์Šต์„ ๋‚˜ํƒ€๋‚ด๊ธฐ๋„ ํ•œ๋‹ค. ์ƒํƒœ ์ˆ˜์—๋”ฐ๋ฅธ๋ชจ๋ธ์˜์„ฑ๋Šฅ์„ํ‰๊ฐ€ํ•˜๊ธฐ์œ„ํ•ด๋‹ค์Œ๋„ค๊ฐ€์ง€์ •๋ณด๊ธฐ์ค€์„์‚ฌ์šฉํ•œ๋‹ค. L์€๋ชจ๋ธ์˜๊ฐ€๋Šฅ๋„ํ•จ์ˆ˜๋ฅผ๋‚˜ํƒ€๋‚ด๊ณ ,M์€์ „์ฒด๊ด€์ธกํ•œ๊ธฐ๊ฐ„์˜๋ฐ์ดํ„ฐ์˜์ˆ˜๋ฅผ์˜๋ฏธํ•˜๋ฉฐ, k๋Š”๋ชจ๋ธ์—์„œ์ถ”์ •๋œ๋ชจ์ˆ˜์˜์ˆ˜๋ฅผ๋‚˜ํƒ€๋‚ธ๋‹ค.๋„ค๊ฐ€์ง€์ง€ํ‘œ๋ชจ๋‘๊ฐ๊ฐ์˜๊ธฐ์ค€๊ฐ’์ด์ž‘์„์ˆ˜๋ก๋”์ข‹์€๋ชจ๋ธ์ด๋ผ๊ณ ํŒ๋‹จํ• ์ˆ˜์žˆ๋‹ค.

(i) Akaike information criterion (AIC): AIC = โˆ’2 ln L + 2k.

(ii) Bayesin information criterion (BIC): BIC = โˆ’2 ln L + k ln M.

(iii) hannan-quinn information criterion (HQC): HQC = โˆ’2 ln L + 2k ln(ln M).

(iv) bozdogan consistent Akaike information criterion (CAIC): CAIC = โˆ’2 ln L + k(ln M + 1).

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468 Hajin Kang, Beom Seuk Hwang

3.2.2.๋ชจ๋ธํ•™์Šต

HMM์˜๋ชจ์ˆ˜๋ฅผ์ถ”์ •ํ•˜๊ธฐ์œ„ํ•ด๋ฐ”์›€-์›ฐ์น˜์•Œ๊ณ ๋ฆฌ์ฆ˜์„์ ์šฉํ•œ๋‹ค.์ด๋•Œ,์ „์ฒด๋ฐ์ดํ„ฐ๋ฅผํ•™์Šต๋ฐ์ดํ„ฐ์™€์‹คํ—˜๋ฐ์ดํ„ฐ๋กœ๋‚˜๋ˆ„๊ณ ,ํ•™์Šต๋ฐ์ดํ„ฐ๋ฅผ์ž„์˜์˜๋‹จ์œ„๋ธ”๋ก์œผ๋กœ๋ถ„ํ• ํ•˜์—ฌ๊ฐ๊ฐ๋ธ”๋ก๋ณ„ํ•™์Šต์„์ง„ํ–‰ํ•œ๋‹ค.๊ทธ๋ฆฌ๊ณ ์ž„์˜์˜์‹œ์ ์— ๋Œ€ํ•ด์„œ ๊ด€์ธก์น˜๊ฐ€ ์ฃผ์–ด์ง„ ๊ฒฝ์šฐ, ๊ณผ๊ฑฐ์— ๋น„์Šทํ•œ ๊ฐ€๋Šฅ๋„๋ฅผ ๋‚˜ํƒ€๋‚ธ ์œ ์‚ฌ ๋ฐ์ดํ„ฐ๋ฅผ ์ฐพ๋Š” ๋ฐฉ๋ฒ•์„ ์ด์šฉํ•ด๋‹ค์Œ ์‹œ์ ์— ๋Œ€ํ•œ ๊ฐ€๊ฒฉ์„ ์˜ˆ์ธกํ•œ๋‹ค (Hassan๊ณผ Nath, 2005). ์ดํ›„์— ๊ด€์ธก ๋ฐ์ดํ„ฐ๊ฐ€ ์ถ”๊ฐ€๋˜๋ฉด ์ด๋ฅผ ๋‹ค์‹œ ํ•™์Šต๋ฐ์ดํ„ฐ๋กœํ•˜์—ฌ๋ชจ๋ธ์„์žฌํ•™์Šตํ•˜๊ณ ๋‹ค์Œ์‹œ์ ์˜์˜ˆ์ธก์„์ง„ํ–‰ํ•œ๋‹ค.

์ฃผ๊ฐ€์ง€์ˆ˜ ๋ฐ์ดํ„ฐ์— ์ ์šฉํ•˜์—ฌ ์˜ˆ์ธก ๊ณผ์ •์„ ์กฐ๊ธˆ ๋” ์ž์„ธํžˆ ์‚ดํŽด๋ณด๋ฉด ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค. ์šฐ์„ , ํ•™์Šต ๋ฐ์ดํ„ฐ์—์„œ๊ธธ์ด๊ฐ€ D์ธ ๊ณ ์ •๋œ ๊ตฌ๊ฐ„์„ ์„ ํƒํ•œ๋‹ค. HMM์˜ ๋ชจ์ˆ˜์ธ ฮป๋ฅผ ์ถ”์ •ํ•˜๊ธฐ ์œ„ํ•ด T โˆ’ D + 1๋ถ€ํ„ฐ T๊นŒ์ง€ ๊ตฌ๊ฐ„์„ ๋‹จ์œ„๋ธ”๋ก์œผ๋กœํ•˜์—ฌํ•™์Šต๋ฐ์ดํ„ฐ๋กœ์‚ฌ์šฉํ•œ๋‹ค.์ฃผ๊ฐ€์ง€์ˆ˜๋ฐ์ดํ„ฐ๋Š”์—ฐ์†ํ˜•๋ฐ์ดํ„ฐ์ด๋ฏ€๋กœ๊ฐ€์šฐ์‹œ์•ˆ๋ถ„ํฌ๋ฅผ๋”ฐ๋ฅธ๋‹ค๊ณ ๊ฐ€์ •ํ•˜๋ฉฐ, HMM์˜ ๋ชจ์ˆ˜์ธ ฮป = {A, B, p}์—์„œ ํ–‰๋ ฌ B๋Š” ๊ฐ€์šฐ์‹œ์•ˆ ๋ถ„ํฌ์˜ ํ‰๊ท  ยต์™€ ํ‘œ์ค€ํŽธ์ฐจ ฯƒ๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค.์ฃผ๊ฐ€์ง€์ˆ˜๋ฐ์ดํ„ฐ์—์„œ๊ด€์ธก๊ฐ€๋Šฅํ•œ์ˆ˜์—ด์€์ข…๊ฐ€,์‹œ๊ฐ€,๊ณ ๊ฐ€,์ €๊ฐ€๋ฅผ์˜๋ฏธํ•˜๋ฉฐ๋‹ค์Œ๊ณผ๊ฐ™์ด๋‚˜ํƒ€๋‚ผ์ˆ˜์žˆ๋‹ค.

O ={O(1)

t ,O(2)t ,O(3)

t ,O(4)t , t = T โˆ’ D + 1,T โˆ’ D + 2, . . . ,T

}.

์ž„์˜์˜์ดˆ๊ธฐ๋ชจ์ˆ˜์™€๋ฐ์ดํ„ฐ๋ฅผ์ด์šฉํ•˜์—ฌ๊ด€์ธก๊ฐ’์˜ํ™•๋ฅ  P(O|ฮป)๋ฅผ๊ณ„์‚ฐํ• ์ˆ˜์žˆ๋‹ค.๊ทธ์ดํ›„์—”๋ฐ์ดํ„ฐ๋ธ”๋ก์„์ผ๋ณ„๋กœ์ด๋™์‹œ์ผœ๋‹ค์Œ์˜์ƒˆ๋กœ์šด๊ด€์ธก๋ฐ์ดํ„ฐ๋ฅผ์–ป์œผ๋ฉฐํ™•๋ฅ  P(Onew|ฮป)๋ฅผ๊ณ„์‚ฐํ• ์ˆ˜์žˆ๋‹ค.

Onew ={O(1)

t ,O(2)t ,O(3)

t ,O(4)t , t = T โˆ’ D,T โˆ’ D + 1, . . . ,T โˆ’ 1

}.

์ด๋Ÿฌํ•œ๊ณผ์ •์„๋ฐ˜๋ณตํ•˜์—ฌ P(Oโˆ—|ฮป) ' P(O|ฮป)๋ฅผ๋งŒ์กฑํ•˜๋Š”๋ฐ์ดํ„ฐ Oโˆ—๋ฅผ์ฐพ์•„๋‚ธ๋‹ค.

Oโˆ— ={O(1)

t ,O(2)t ,O(3)

t ,O(4)t , t = T โˆ— โˆ’ D + 1,T โˆ— โˆ’ D + 2, . . . ,T โˆ—

}.

๋งˆ์ง€๋ง‰์œผ๋กœ ๊ด€์ธก ๊ฐ€๋Šฅํ•œ ์ˆ˜์—ด ์ค‘ ์ข…๊ฐ€๋ฅผ ์˜ˆ๋กœ ๋“ ๋‹ค๋ฉด T + 1์‹œ์ ์˜ ์ข…๊ฐ€O(1)T+1์˜ ๊ฐ€๊ฒฉ์€ ๋‹ค์Œ ์‹์„ ์ด์šฉํ•˜์—ฌ

๊ณ„์‚ฐํ• ์ˆ˜์žˆ๋‹ค.

O(1)T+1 = O(1)

T +(O(1)

T โˆ—+1 โˆ’ O(1)T โˆ—

)ร— sign(P(O|ฮป) โˆ’ P(Oโˆ—|ฮป)).

๋งˆ์ฐฌ๊ฐ€์ง€๋กœ T + 2์‹œ์ ์˜๊ฐ€๊ฒฉ์„์˜ˆ์ธกํ•˜๊ธฐ์œ„ํ•ด์„œ๋Š”์ƒˆ๋กœ์šด๋ฐ์ดํ„ฐ O๋ฅผํ•™์Šต๋ฐ์ดํ„ฐ๋กœ์‚ฌ์šฉํ•œ๋‹ค.

O ={O(1)

t ,O(2)t ,O(3)

t ,O(4)t , t = T โˆ’ D + 2,T โˆ’ D + 3, . . . ,T + 1

}.

์ฒ˜์Œ์˜ˆ์ธก๊ณผ์ •์—์„œ์ถ”์ •๋œ HMM์˜๋ชจ์ˆ˜ ฮป๋Š”๋‘๋ฒˆ์งธ์˜ˆ์ธก์„์ง„ํ–‰ํ• ๋•Œ์ดˆ๊ธฐ๋ชจ์ˆ˜๋กœ์‚ฌ์šฉํ•˜๋ฉฐ,๋‚˜๋จธ์ง€๋Š”์œ„์˜๊ณผ์ •์„๋™์ผํ•˜๊ฒŒ๋ฐ˜๋ณตํ•˜์—ฌ์˜ˆ์ธก์„์ง„ํ–‰ํ•œ๋‹ค.

3.2.3.๋ชจ๋ธ๊ฒ€์ฆ

์˜ˆ์ธก ๊ฒฐ๊ณผ๋ฅผ ๋น„๊ตํ•˜๊ธฐ ์œ„ํ•œ ํšจ์œจ์„ฑ ์ธก๋„๋กœ ํ‰๊ท ์ ˆ๋Œ€๋ฐฑ๋ถ„์œจ์˜ค์ฐจ(MAPE)์™€ ํ‰๊ท ์ ˆ๋Œ€์˜ค์ฐจ(AAE), ์ œ๊ณฑ๊ทผํ‰๊ท ์ œ๊ณฑ์˜ค์ฐจ(RMSE)๋ฅผ์‚ฌ์šฉํ•˜๋ฉฐ๋‹ค์Œ๊ณผ๊ฐ™์ด์ •์˜๋œ๋‹ค.

(i) mean absolute percentage error (MAPE)

MAPE =1N

Nโˆ‘i=1

|True(i) โˆ’ Predicted(i)|True(i)

,

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A hidden Markov model for predicting global stock market index 469

Table 2: Criterion values for the number of states in KOSPI200

Criteria 2 States 3 States 4 States 5 States 6 StatesAIC 41669.8 39766.9 38283.5 37099.6 36508.5BIC 41698.9 39830.8 38393.9 37268.1 36746.8HQC 41670.1 39767.5 38284.6 37101.2 36510.8CAIC 41698.9 39830.8 38393.9 37268.1 36746.8

(ii) average absolute error (AAE)

AAE =1N

Nโˆ‘i=1

|True(i) โˆ’ Predicted(i)|,

(iii) root-mean-square error (RMSE)

RMSE =

โˆšโˆš1N

Nโˆ‘i=1

(True(i) โˆ’ Predicted(i))2.

์„ธ๊ฐ€์ง€์ธก๋„๋ชจ๋‘์ƒ๋Œ€์ ์œผ๋กœ์ž‘์„์ˆ˜๋ก์˜ˆ์ธก์ด์ž˜์ด๋ฃจ์–ด์กŒ๋‹ค๊ณ ํŒ๋‹จํ• ์ˆ˜์žˆ๋‹ค.

3.3.๋ชจ๋ธ์„ค์ •

์ฃผ๊ฐ€์ง€์ˆ˜๋ฐ์ดํ„ฐ๋Š”์—ฐ์†ํ˜•๋ณ€์ˆ˜์ด๋ฏ€๋กœ 2.3์—์„œ์–ธ๊ธ‰ํ•œ๋‹ค๋ณ€๋Ÿ‰ Gaussian HMM์„์‚ฌ์šฉํ• ๊ฒƒ์ด๋‹ค.๋ชจ๋ธ์„์„ค์ •ํ• ๋•Œ์€๋‹‰์ƒํƒœ์˜์ˆ˜๋ฅผ์ถฉ๋ถ„ํ•˜๊ฒŒ์„ค์ •ํ•˜๋ฉด๋ชจํ˜•์˜์„ ํƒํญ๋„๋‹ค์–‘ํ•˜๊ณ ๋”์ ํ•ฉํ•œ๋ชจํ˜•์ด์„ ํƒ๋ ์ˆ˜๋Š”์žˆ์œผ๋‚˜,ํŒŒ๋ผ๋ฏธํ„ฐ์˜ํ•ด์„๊ณผ๋ชจํ˜•์—๋Œ€ํ•œ์ดํ•ด๊ฐ€์–ด๋ ต๋‹ค๋Š”๋‹จ์ ์ด์žˆ๋‹ค.๋”ฐ๋ผ์„œ์ ˆ์•ฝ์„ฑ์˜์›๋ฆฌ(principle of parsimony)๋ฅผ ๊ณ ๋ คํ•˜์—ฌ ์€๋‹‰ ์ƒํƒœ์˜ ์ˆ˜๋Š” 2์—์„œ 6๊นŒ์ง€๋กœ ์ œํ•œํ•˜๊ณ , ๊ฐ ์ƒํƒœ์˜ ์ˆ˜์— ๋”ฐ๋ผ AIC, BIC, HQC, CAIC ๊ธฐ์ค€์„์‚ฌ์šฉํ•˜์—ฌ ์ ์ ˆํ•œ ์€๋‹‰ ์ƒํƒœ์˜ ์ˆ˜๋ฅผ ๊ฒฐ์ •ํ•˜์˜€๋‹ค. ๊ธฐ์ค€๊ฐ’์ด ์ž‘์„์ˆ˜๋ก ๋” ์ข‹์€ ๋ชจํ˜•์ด๋ฉฐ, Table 2์€ KOSPI200์ง€์ˆ˜์—๋Œ€ํ•œ์ƒํƒœ์˜์ˆ˜์—๋”ฐ๋ฅธ๊ธฐ์ค€๊ฐ’๋“ค์„๋‚˜ํƒ€๋‚ด๊ณ ์žˆ๋‹ค.

๊ตญ๋‚ด KOSPI200์ง€์ˆ˜๋ฟ๋งŒ์•„๋‹ˆ๋ผํ•ด์™ธ์ฃผ๊ฐ€์ง€์ˆ˜๋“ค๋ชจ๋‘ 4๊ฐ€์ง€๊ธฐ์ค€์—์˜ํ•ด๊ฒฐ์ •๋œ์ตœ์ ์˜์ƒํƒœ์ˆ˜๋Š” 6๊ฐœ์ด๋‹ค. KOSPI200์˜๊ฒฝ์šฐ์ƒํƒœ์˜์ˆ˜๋ฅผ์ œํ•œ์—†์ด์ถฉ๋ถ„ํžˆํฌ๊ฒŒํ•˜๋ฉด, AIC, HQC๋ฅผ๊ธฐ์ค€์œผ๋กœ๋Š” 25 States๊ฐ€์ตœ์ ์ธ๊ฒƒ์œผ๋กœ, BIC, CAIC๋ฅผ๊ธฐ์ค€์œผ๋กœ๋Š” 15 States๊ฐ€์ตœ์ ์ธ๊ฒƒ์œผ๋กœํ™•์ธํ• ์ˆ˜์žˆ์—ˆ์œผ๋‚˜์ƒํƒœ์˜์ˆ˜๊ฐ€ํฐ๊ฒฝ์šฐ๋ชจํ˜•์„์œ„ํ•ด ์ถ”์ •ํ•ด์•ผ ํ•  ํŒŒ๋ผ๋ฏธํ„ฐ์˜ ์ˆ˜๋„ ๊ธฐํ•˜๊ธ‰์ˆ˜์ ์œผ๋กœ ์ฆ๊ฐ€ํ•˜๋ฏ€๋กœ ์—ฌ๋Ÿฌ ๊ฐ€์ง€ ํšจ์œจ์„ฑ์„ ์œ„ํ•ด ์ œํ•œ๋œ ์ƒํƒœ์—์„œ

์ตœ์ ์˜ ์ƒํƒœ ์ˆ˜์ธ 6๊ฐœ๋ฅผ ์ตœ์ ์œผ๋กœ ์„ ํƒํ•˜๊ธฐ๋กœ ํ•˜์˜€๋‹ค. ์ตœ์ ์˜ ๋ชจํ˜•์œผ๋กœ ์„ ํƒ๋œ 6 States HMM์„ ๊ธฐ๋ฐ˜์œผ๋กœ์ ํ•ฉํ•œ๋ชจ๋ธ์˜ 100์˜์—…์ผ์‹œ์ ์˜ˆ์ธก์—๋Œ€ํ•œํŒŒ๋ผ๋ฏธํ„ฐ์˜๊ฐ’์€ Figure 4์—์„œํ™•์ธํ• ์ˆ˜์žˆ๊ณ ,๊ทธํ•ด์„์€๋‹ค์Œ๊ณผ๊ฐ™์ด ํ•  ์ˆ˜ ์žˆ๋‹ค. ์ดˆ๊ธฐ ํ™•๋ฅ ์ด p = (1, 0, 0, 0, 0, 0)์œผ๋กœ ์ฃผ์–ด์กŒ์„ ๋•Œ t = 1 ์‹œ์ ์—์„œ q1 = S 1 ๊ฐ’์„ ๊ฐ–๊ณ , t = 2์‹œ์ ์—์„œ q2 = S 1 ๊ฐ’์„ ๊ฐ€์งˆ ํ™•๋ฅ ์ด 0.995๊ฐ€ ๋จ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. ๋งˆ์ฐฌ๊ฐ€์ง€๋กœ t = 2 ์‹œ์ ์—์„œ q2 = S 2 ๊ฐ’์„ ๊ฐ€์งˆ

ํ™•๋ฅ ์€ 0์—๊ทผ์ ‘ํ•˜๊ณ , q2 = S 3 ๊ฐ’์„๊ฐ€์งˆํ™•๋ฅ ์€ 0.007์ด๋œ๋‹ค.์ผ๋ฐ˜ํ™”ํ•˜๋ฉด,์ „์ดํ™•๋ฅ ํ–‰๋ ฌ A์˜ iํ–‰ j์—ด์›์†Œ๋Š”์ž„์˜์˜ t ์‹œ์ ์—์„œ qt = S i๊ฐ’์„ ๊ฐ–๊ณ  t + 1 ์‹œ์ ์—์„œ qt+1 = S j ๊ฐ’์„ ๊ฐ€์งˆ ํ™•๋ฅ ์„ ๋‚˜ํƒ€๋‚ธ๋‹ค. ํ–‰๋ ฌ์˜ ๋Œ€๊ฐ์›์†Œ๊ฐ’์ด๋Œ€๋ถ€๋ถ„ 0.95๋ณด๋‹คํฌ๊ฒŒ๋‚˜ํƒ€๋‚˜๋Š”๊ฒƒ์œผ๋กœ๋ณด์•„๋™์ผ์ƒํƒœ๋กœ์ „์ด๋ ํ™•๋ฅ ์ด๊ฐ€์žฅํฐ๊ฒƒ์„์•Œ์ˆ˜์žˆ๋‹ค.

์‹ค์ œ ์ฃผ๊ฐ€์ง€์ˆ˜ ๋ฐ์ดํ„ฐ ๋ถ„์„์—์„œ ๋‹ค๋ณ€๋Ÿ‰ ๊ฐ€์šฐ์‹œ์•ˆ ๋ถ„ํฌ๋ฅผ ๊ฐ€์ •ํ–ˆ์œผ๋ฏ€๋กœ, ์ถœ๋ ฅํ™•๋ฅ ํ–‰๋ ฌ B๋Š” ํŒŒ๋ผ๋ฏธํ„ฐ ยต

์™€ ฮฃ๋ฅผ์˜๋ฏธํ•œ๋‹ค.ํ–‰๋ ฌ ยต์˜์˜๋ฏธ๋Š”๋‹ค์Œ๊ณผ๊ฐ™๋‹ค.์ž„์˜์˜ t ์‹œ์ ์—์„œ 1ํ–‰์€์ฒซ๋ฒˆ์งธ์ƒํƒœ๊ฐ€ S 1๊ฐ’์„๊ฐ€์งˆ๋•Œ,์ฆ‰qt = S 1์ผ๋•Œ์ข…๊ฐ€,์‹œ๊ฐ€,๊ณ ๊ฐ€,์ €๊ฐ€์—ํ•ด๋‹นํ•˜๋Š”ํ‰๊ท ๊ฐ’๋“ค์˜๋ฒกํ„ฐ๋ฅผ์˜๋ฏธํ•œ๋‹ค.์ฆ‰, ยตik๋Š”์ƒํƒœ๊ฐ€ S i์ผ๋•Œ,์‹ฌ๋ณผ(Symbols) vk๊ฐ’์—๋Œ€ํ•œํ‰๊ท ์„์˜๋ฏธํ•œ๋‹ค.ํ•ด๋‹น์˜ˆ์—์„œ๊ฐ€๋Šฅํ•œ์‹ฌ๋ณผ์€ {v1, v2, v3, v4}์ด๊ณ ๊ฐ๊ฐ์€์ข…๊ฐ€,์‹œ๊ฐ€,๊ณ ๊ฐ€, ์ €๊ฐ€๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค. ํ–‰๋ ฌ ฮฃ๋„ ๋งˆ์ฐฌ๊ฐ€์ง€๋กœ ์ข…๊ฐ€, ์‹œ๊ฐ€, ๊ณ ๊ฐ€, ์ €๊ฐ€์— ํ•ด๋‹นํ•˜๋Š” ๊ณต๋ถ„์‚ฐํ–‰๋ ฌ์ด ์ƒํƒœ์˜ ์ˆ˜๋งŒํผ

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470 Hajin Kang, Beom Seuk Hwang

Figure 4: 6 states HMM parameters in KOSPI200.

6๊ฐœ๊ฐ€ ๋‚˜ํƒ€๋‚จ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. Figure 4์„ ํ†ตํ•ด์„œ ์ƒํƒœ๊ฐ€ S i์ผ ๋•Œ, ์ด์— ํ•ด๋‹นํ•˜๋Š” ๊ฐ๊ฐ์˜ ๊ณต๋ถ„์‚ฐ์„ ํ™•์ธํ•  ์ˆ˜์žˆ์œผ๋ฉฐ,ํ‰๊ท ๊ณผ๊ณต๋ถ„์‚ฐํ–‰๋ ฌ๋ชจ๋‘์ƒํƒœ์—๋”ฐ๋ผ๊ฐ’์˜์ˆ˜์ค€์ด๊ตฐ์ง‘ํ™”๋œ๊ฒƒ์ฒ˜๋Ÿผ๊ตฌ๋ถ„๋˜์–ด๋‚˜ํƒ€๋‚œ๊ฒƒ์„ํ™•์ธํ• ์ˆ˜์žˆ๋‹ค.

3.4.๋ถ„์„๊ฒฐ๊ณผ

Figure 5๋Š” KOSPI200 ์ง€์ˆ˜์˜ ์ข…๊ฐ€, ์‹œ๊ฐ€, ๊ณ ๊ฐ€, ์ €๊ฐ€์— ๋Œ€ํ•œ 2019๋…„ 8์›” 5์ผ๋ถ€ํ„ฐ 2019๋…„ 12์›” 30์ผ๊นŒ์ง€ 100์˜์—…์ผ ๋™์•ˆ์˜ ์˜ˆ์ธก ๊ฒฐ๊ณผ๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค. ์‹ค์ œ ์ฃผ๊ฐ€์ง€์ˆ˜ ๊ฐ€๊ฒฉ์€ ๋ถ‰์€์ƒ‰ ์ ์„ , ๋ชจ๋ธ์„ ํ†ตํ•œ ์˜ˆ์ธก๊ฐ€๊ฒฉ์€ ๊ฒ€์ •์ƒ‰์‹ค์„ ์œผ๋กœํ‘œํ˜„๋˜๊ณ ์žˆ๋‹ค.์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ(HMM)์„์ด์šฉํ•œ์˜ˆ์ธก์ด์ „์ฒด์ ์ธ์ฃผ๊ฐ€์ง€์ˆ˜์›€์ง์ž„์ด๋‚˜์ถ”์ด๋ฅผ์ž˜ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ์Œ์„ ๋ณด์—ฌ์ฃผ๊ณ  ์žˆ๋‹ค. ์˜ˆ์ธก์˜ ์„ฑ๊ณผ๋ฅผ ํ™•์ธํ•˜๊ธฐ ์œ„ํ•ด ํ•™์Šต ๋ฐ์ดํ„ฐ์™€ ์‹คํ—˜ ๋ฐ์ดํ„ฐ๋กœ ๋‚˜๋ˆˆ ์ „์ฒด๋ฐ์ดํ„ฐ์ค‘์—์„œ์‹คํ—˜๋ฐ์ดํ„ฐ์™€์˜์˜ˆ์ธก์˜ค์ฐจ๋ฅผํ™•์ธํ•˜์˜€๋‹ค. Table 3์—๋Š” HMM๊ณผ๋น„๊ต๋ชจ๋ธ์ธ์„œํฌํŠธ๋ฒกํ„ฐํšŒ๊ท€(support vector regression; SVR) ๋ชจ๋ธ (Basak ๋“ฑ, 2007)์„ ํ†ตํ•ด์„œ ๋‚˜์˜จ ์˜ˆ์ธก ์˜ค์ฐจ๋ฅผ ๋น„๊ตํ•˜๊ณ  ์žˆ๋‹ค. HMM ๋ชจ๋ธ์ด SVR ๋ชจ๋ธ๋ณด๋‹ค ์ „๋ฐ˜์ ์œผ๋กœ ๋” ์ž‘์€ ์˜ˆ์ธก ์˜ค์ฐจ๋ฅผ ๋ณด์—ฌ์ฃผ๊ณ  ์žˆ์ง€๋งŒ, ์ œ๊ณฑ๊ทผํ‰๊ท ์ œ๊ณฑ์˜ค์ฐจ(RMSE)์˜ ๊ฒฝ์šฐ์ฃผ๊ฐ€์ง€์ˆ˜์‹œ๊ฐ€์™€๊ณ ๊ฐ€๋Š” SVR๋ชจ๋ธ์ด๋”์ž‘์€์˜ˆ์ธก์˜ค์ฐจ๋ฅผ๊ฐ€์ง€๊ณ ์žˆ๋‹ค. KOSPI200์˜๊ฒฝ์šฐ๋น„๊ต๋Œ€์ƒ์œผ๋กœํ•œSVR ๋ชจ๋ธ์ด RBF ์ปค๋„(radial basis function kernel)์„ ์ด์šฉํ•œ ๊ฒฐ๊ณผ์ด์ง€๋งŒ, ๊ฐ๊ฐ์˜ ์ฃผ๊ฐ€์ง€์ˆ˜ ๋ฐ์ดํ„ฐ์— ๋”ฐ๋ผ์„œ์„ ํ˜•(linear), ๋‹คํ•ญ(polynomial), ์‹œ๊ทธ๋ชจ์ด๋“œ(sigmoid) ์ปค๋„ ๋“ฑ๊ณผ ๊ฐ™์€ ๋‹ค๋ฅธ ์˜ต์…˜์„ ์ด์šฉํ•˜๊ฒŒ ๋˜๋ฉด ๊ฒฐ๊ณผ๋Š” ์กฐ๊ธˆ์”ฉ ๋‹ฌ๋ผ์งˆ ์ˆ˜ ์žˆ์„ ๊ฒƒ์ด๋‹ค. ์„œํฌํŠธ ๋ฒกํ„ฐ ํšŒ๊ท€ ๋ชจ๋ธ์€ ์ˆœ์„œ์— ๋”ฐ๋ฅธ ๊ทผ์ ‘ํ•œ ๋ฐ์ดํ„ฐ์˜ ์กฐ๊ฑด๋ถ€ ์˜์กด์„ฑ์— ๋Œ€ํ•œ๊ณ ๋ ค๊ฐ€๋ถ€์กฑํ•˜๊ณ ,๋ชจํ˜•์ ํ•ฉ๋ฐ์˜ˆ์ธก๊นŒ์ง€์˜๊ณ„์‚ฐ์‹œ๊ฐ„์ด HMM๋ณด๋‹ค์ƒ๋Œ€์ ์œผ๋กœ๋งŽ์ด์†Œ์š”๋˜๋Š”๋‹จ์ ์„๊ฐ€์ง€๊ณ ์žˆ๋‹ค. HMM๋ชจ๋ธ์€๊ด€์ฐฐ๊ฐ€๋Šฅํ•œํ™•๋ฅ ๊ณผ์ •์˜๊ฒฝ์šฐ๋งˆ๋ฅด์ฝ”ํ”„์—ฐ์‡„๊ฐ€์ฃผ์–ด์ง„์ƒํ™ฉ์—์„œ์กฐ๊ฑด๋ถ€๋…๋ฆฝ์ด๋ฉฐ,๊ฐ์‹œ์ ์˜์กฐ๊ฑด๋ถ€๋ถ„ํฌ๋Š”์˜ค์งํ•ด๋‹น์‹œ์ ์˜๋งˆ๋ฅด์ฝ”ํ”„์—ฐ์‡„์—๋งŒ์˜์กดํ•˜๋Š”๊ธฐ๋ณธ๊ตฌ์กฐ๋ฅผ๊ฐ€์ง€๊ณ ์žˆ๋‹ค.์ด๋Š”์ฃผ๊ฐ€์ง€์ˆ˜

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A hidden Markov model for predicting global stock market index 471

Figure 5: Prediction results for closing, open, high and low prices in KOSPI200.

Table 3: Prediction error for closing, open, high and low prices in KOSPI200

Model Method Closing Open High LowMAPE 0.0088 0.0079 0.0083 0.0081

HMM AAE 2.41 2.18 2.29 2.21RMSE 3.05 2.95 2.84 2.92MAPE 0.0098 0.0083 0.0083 0.0085

SVR AAE 2.69 2.28 2.29 2.31RMSE 3.39 2.91 2.73 2.95

์›€์ง์ž„์— ์ ํ•ฉํ•œ ๊ตฌ์กฐ๋ผ๊ณ  ํ•  ์ˆ˜ ์žˆ๋Š”๋ฐ ์ž„์˜์˜ ์‹œ์ ์˜ ์ฃผ๊ฐ€์ง€์ˆ˜๊ฐ€ ์€๋‹‰๋œ ์—ฌ๋Ÿฌ ์ƒํƒœ์— ์˜ํ•ด ์˜ํ–ฅ์„ ๋ฐ›์œผ๋ฉฐ

๋งˆ๋ฅด์ฝ”ํ”„ ๊ณผ์ •์„ ๋”ฐ๋ฅธ๋‹ค๊ณ  ๊ฐ€์ •์„ ํ•  ์ˆ˜ ์žˆ๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค. ๋˜ํ•œ HMM ๋ชจ๋ธ์€ ํŒŒ๋ผ๋ฏธํ„ฐ ๋“ฑ์„ ์ด์šฉํ•˜์—ฌ ๋ชจ๋ธ์„์„ค๋ช…๋ฐํ•ด์„ํ• ์ˆ˜์žˆ์œผ๋ฏ€๋กœ๋ฐ์ดํ„ฐ์˜ํŠน์„ฑ์ƒ HMM์„์ด์šฉํ•œ์˜ˆ์ธก์ด๋”์ข‹์€๊ฒฐ๊ณผ๋ฅผ์ œ๊ณตํ•˜๊ณ ์žˆ๋‹ค๊ณ ๋ณผ์ˆ˜์žˆ๋‹ค.

Figure 6๋Š” ํ•ด์™ธ ์ฃผ๊ฐ€์ง€์ˆ˜์— ๋Œ€ํ•œ HMM์„ ์ด์šฉํ•œ ์ข…๊ฐ€์˜ ์˜ˆ์ธก ๊ฒฐ๊ณผ๋ฅผ ๋‚˜ํƒ€๋‚ด๋Š”๋ฐ ์‹ค์ œ ์ฃผ๊ฐ€์ง€์ˆ˜ ๊ฐ€๊ฒฉ์€ ๋ถ‰์€์ƒ‰ ์ ์„ , ๋ชจ๋ธ์„ ํ†ตํ•œ ์˜ˆ์ธก๊ฐ€๊ฒฉ์€ ๊ฒ€์ •์ƒ‰ ์‹ค์„ ์œผ๋กœ ํ‘œํ˜„ํ•˜๊ณ  ์žˆ๋‹ค. Table 4๋Š” ์ด์— ๋Œ€ํ•œ ์˜ˆ์ธก ์˜ค์ฐจ๋ฅผ๋น„๊ตํ•œ๊ฒฐ๊ณผ๋ฅผ๋ณด์—ฌ์ฃผ๊ณ ์žˆ๋‹ค.

๋ณธ์—ฐ๊ตฌ์—์„œ์ ์šฉํ•œ HMM์ด์ตœ๊ทผ์ฃผ๊ฐ€์˜ˆ์ธก์—๋งŽ์ดํ™œ์šฉ๋˜๊ณ ์žˆ๋Š” SVR์—๋ชป์ง€์•Š๊ฒŒ์ „๋ฐ˜์ ์œผ๋กœ์šฐ์ˆ˜ํ•œ์˜ˆ์ธก์ •ํ™•๋„๋ฅผ๋ณด์ด๊ณ ์žˆ์Œ์„ํ™•์ธํ• ์ˆ˜์žˆ๋‹ค.์ด๋Š”๊ตญ๋‚ด๋ฐํ•ด์™ธ์ฃผ๊ฐ€์ง€์ˆ˜๋ฅผ์˜ˆ์ธกํ•˜๊ธฐ์œ„ํ•œ๋ฐฉ๋ฒ•์œผ๋กœ HMM์ดํšจ๊ณผ์ ์ธ์ˆ˜๋‹จ์ด๋ ์ˆ˜์žˆ๋‹ค๋Š”์ ์„๋’ท๋ฐ›์นจํ•˜๋Š”์—ฐ๊ตฌ๊ฒฐ๊ณผ๋ผ๊ณ ํ• ์ˆ˜์žˆ๋‹ค.

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Figure 6: Prediction results for closing prices in NIKKEI225, HSI, S&P500 and FTSE100.

Table 4: Prediction error for closing prices in NIKKEI225, HSI, S&P500 and FTSE100

Model Method NIKKEI225 HSI S&P500 FTSE100MAPE 0.0082 0.0113 0.0080 0.0086

HMM AAE 182.73 303.18 23.98 62.64RMSE 243.43 379.43 33.06 78.65MAPE 0.0085 0.0112 0.0084 0.0086

SVR AAE 190.91 298.41 25.18 62.90RMSE 246.36 388.83 33.47 82.56

4.๊ฒฐ๋ก ๋ฐ๋…ผ์˜

๋ณธ๋…ผ๋ฌธ์—์„œ๋Š”์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ์„๊ธฐ๋ฐ˜์œผ๋กœ๊ตญ๋‚ด KOSPI200์ฃผ๊ฐ€์ง€์ˆ˜์™€ํ•ด์™ธ NIKKEI225, HSI, S&P500,FTSE100์ฃผ๊ฐ€์ง€์ˆ˜์˜ˆ์ธก์—์ ์šฉํ•˜์—ฌ์–ผ๋งˆ๋‚˜์šฐ์ˆ˜ํ•œ์˜ˆ์ธก์ •ํ™•๋„๋ฅผ๋‚˜ํƒ€๋‚ด๋Š”์ง€์‹ค์ฆ๋ถ„์„์„์‹œ๋„ํ•˜์˜€๋‹ค. AIC,BIC, HQC, CAIC๊ธฐ์ค€์„์ด์šฉํ•ด๋ชจ๋ธ์˜์ตœ์ ์ƒํƒœ์ˆ˜๋ฅผ๊ฒฐ์ •ํ•˜์˜€๊ณ ,์ด๋ฅผํ†ตํ•ด์ƒ์„ฑํ•œ๋ชจํ˜•์œผ๋กœ์ฃผ๊ฐ€์ง€์ˆ˜๋“ค์˜์›€์ง์ž„์„์ž˜๋”ฐ๋ผ๊ฐ€๋ฉฐ๊ฐ€๊ฒฉ๋˜ํ•œ์ž˜์˜ˆ์ธกํ•˜๋Š”์ง€๋ฅผ์‚ดํŽด๋ณด์•˜๋‹ค.๊ทธ๊ฒฐ๊ณผ, HMM๋ฐฉ๋ฒ•์ด๋น„๊ต๋ชจํ˜•์ธ์„œํฌํŠธ๋ฒกํ„ฐํšŒ๊ท€๋ชจํ˜•๊ณผ๋น„๊ตํ•ด๋’ค์ฒ˜์ง€์ง€์•Š๋Š”์šฐ์ˆ˜ํ•œ์˜ˆ์ธก์ •ํ™•๋„๋ฅผ๋ณด์ž„์„ํ™•์ธํ• ์ˆ˜์žˆ์—ˆ๋‹ค.ํŠนํžˆ, HMM๋ฐฉ๋ฒ•์€๋งˆ๋ฅด์ฝ”ํ”„์—ฐ์‡„์™€์กฐ๊ฑด๋ถ€๋…๋ฆฝ์ด๋ผ๋Š”๊ธฐ๋ณธ๊ตฌ์กฐ๊ฐ€์ฃผ๊ฐ€๋ฐ์ดํ„ฐ์˜ํŠน์„ฑ์„์ž˜๋ฐ˜์˜ํ• ์ˆ˜์žˆ๋Š”๋ชจํ˜•์ด๋ผ๋Š”์ ์—์„œ

์ฃผ๊ฐ€์ง€์ˆ˜์˜ˆ์ธก์˜์ˆ˜๋‹จ์œผ๋กœ์จ์ ํ•ฉํ•˜๋‹ค๋Š”์‚ฌ์‹ค์„ํ™•์ธํ•˜์˜€๋‹ค.๋˜ํ•œ,๋ณธ์—ฐ๊ตฌ๋ฅผ์ฐธ๊ณ ํ•˜์—ฌ์ถ”ํ›„ํ™˜์œจ๋ฐ์ดํ„ฐ๋‚˜,

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๊ธˆ๋ฆฌ,์ฃผ์‹์˜๋ณ€๋™์„ฑ๋ฟ๋งŒ์•„๋‹ˆ๋ผ์‹ ์šฉ๋ฐ์ดํ„ฐ๋“ฑ๊ธˆ์œต์‹œ์žฅ์˜์—ฌ๋Ÿฌ๋ฐ์ดํ„ฐ์—๋„ HMM๋ฐฉ๋ฒ•์„๋‹ค์–‘ํ•˜๊ฒŒํ™œ์šฉํ• ์ˆ˜์žˆ์„๊ฒƒ์œผ๋กœ๊ธฐ๋Œ€ํ•ด๋ณผ์ˆ˜์žˆ์—ˆ๋‹ค (Idvall๊ณผ Jonsson, 2008; Liu, 2018).

๋ณธ์—ฐ๊ตฌ์˜ํ•œ๊ณ„์ ๋ฐํ–ฅํ›„์—ฐ๊ตฌ๋ฐฉํ–ฅ์€๋‹ค์Œ๊ณผ๊ฐ™๋‹ค.์ฒซ์งธ,๊ด€์ฐฐ๊ฐ€๋Šฅํ•œ๋ฐ์ดํ„ฐ์ธ์ฃผ๊ฐ€์ง€์ˆ˜๋ฐ์ดํ„ฐ๋ชจํ˜•์—๋Œ€ํ•ด ๊ฐ€์šฐ์‹œ์•ˆ ๋ถ„ํฌ ์™ธ์— ๋‹ค์–‘ํ•œ ๋ถ„ํฌ๋ฅผ ๊ฐ€์ •ํ•˜์—ฌ ์ ์šฉํ•˜๊ณ , ๊ธˆ์œต ์‹œ์žฅ์˜ ํŠน์„ฑ์„ ๋ฐ˜์˜ํ•œ ๋” ์ ํ•ฉํ•œ ๋ชจ๋ธ์„์ ์šฉํ•˜๋Š”๊ฒƒ์—๋Œ€ํ•œ์—ฐ๊ตฌ๊ฐ€ํ•„์š”ํ•˜๋‹ค.์ฃผ๊ฐ€์ง€์ˆ˜๋ฐ์ดํ„ฐ์˜๊ฒฝ์šฐ์–‘์ชฝ๊ทน๋‹จ๊ฐ’์˜๋ฐ€๋„๊ฐ€๋”๋†’์€ fat-tailํ˜•ํƒœ์˜๋ถ„ํฌ๋ฅผ๊ฐ€์ง€๊ณ ์žˆ๋‹ค๋Š”๊ฒƒ์ด์•Œ๋ ค์ ธ์žˆ๊ธฐ๋•Œ๋ฌธ์—๊ฐ€์šฐ์‹œ์•ˆ๋ถ„ํฌ์™ธ์—๋กœ๊ทธ์ •๊ทœ๋ถ„ํฌ๋‚˜์›จ์ด๋ธ”๋ถ„ํฌ,์ฝ”์‹œ๋ถ„ํฌ๋“ฑ๊ณผ ๊ฐ™์ด ๋ฐ์ดํ„ฐ์˜ ํŠน์„ฑ์„ ๋ฐ˜์˜ํ•œ HMM์„ ์ ์šฉํ•˜์—ฌ ๊ฒฐ๊ณผ๋ฅผ ๋ณด๋‹ค ๊ฐœ์„ ํ•  ์ˆ˜ ์žˆ์„ ๊ฒƒ์ด๋‹ค. ๋‘˜์งธ, ๋ณธ ๋…ผ๋ฌธ์€2010๋…„๋ถ€ํ„ฐ 2019๋…„๊นŒ์ง€ ํ•ด๋‹น 10๋…„ ๋™์•ˆ์˜ ๋ฐ์ดํ„ฐ ์„ธํŠธ์—๋งŒ ๊ทผ๊ฐ„ํ•˜๊ณ  ์žˆ์–ด์„œ ๊ณผ๊ฑฐ 2008๋…„ ์„ธ๊ณ„ ๊ธˆ์œต์œ„๊ธฐ๋‚˜,ํ˜„์žฌ์ฝ”๋กœ๋‚˜19์‚ฌํƒœ๋กœ์ธํ•œ๊ธˆ์œต์‹œ์žฅ์นจ์ฒด๋“ฑ๊ธˆ์œต์‹œ์žฅ์—ํฐ์ถฉ๊ฒฉ์„์ค€์‚ฌ๊ฑด๋“ค์ดํฌํ•จ๋˜์ง€์•Š์•˜๋‹ค๋Š”ํ•œ๊ณ„์ ์ด์žˆ๋‹ค.์ด์Šˆ๊ฐ€์—†๋Š”๋ณดํ†ต์˜๊ธˆ์œต์‹œ์žฅ์—์„œ์ฃผ์‹์˜์›€์ง์ž„์„์˜ˆ์ธกํ•˜๋Š”๊ฒƒ์™ธ์—๋„๊ธˆ์œต์‹œ์žฅ์—ํฐ์ถฉ๊ฒฉ์ด๋ฐœ์ƒํ–ˆ์„๋•Œ์˜์ฃผ์‹์›€์ง์ž„๋˜ํ•œ์˜ˆ์ธก์ด๊ฐ€๋Šฅํ•˜๋„๋ก์—ฐ๊ตฌ๊ฐ€์ง„ํ–‰๋œ๋‹ค๋ฉด๋ฆฌ์Šคํฌ๊ด€๋ฆฌ์ฐจ์›์—์„œ๋„ํšจ์œจ์ ์œผ๋กœํ™œ์šฉ๋ ์ˆ˜

์žˆ์„๊ฒƒ์œผ๋กœ๊ธฐ๋Œ€ํ•ด๋ณผ์ˆ˜์žˆ๋‹ค.

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Received January 15, 2021; Revised February 5, 2021; Accepted February 15, 2021

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์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ์„์ด์šฉํ•œ๊ตญ๊ฐ€๋ณ„์ฃผ๊ฐ€์ง€์ˆ˜์˜ˆ์ธก

๊ฐ•ํ•˜์ง„a ํ™ฉ๋ฒ”์„1,a

a์ค‘์•™๋Œ€ํ•™๊ต์‘์šฉํ†ต๊ณ„ํ•™๊ณผ

์š” ์•ฝ

์€๋‹‰ ๋งˆ๋ฅด์ฝ”ํ”„ ๋ชจ๋ธ(hidden Markov model, HMM)์€ ์€๋‹‰๋œ ์ƒํƒœ์™€ ๊ด€์ฐฐ ๊ฐ€๋Šฅํ•œ ๊ฒฐ๊ณผ์˜ ๋‘ ๊ฐ€์ง€ ์š”์†Œ๋กœ์ด๋ฃจ์–ด์ง„ํ†ต๊ณ„์ ๋ชจํ˜•์œผ๋กœํ™•๋ฅ ๋ก ์ ์ ‘๊ทผ์ด๊ฐ€๋Šฅํ•˜๊ณ ,๋‹ค์–‘ํ•œ์ˆ˜ํ•™์ ์ธ๊ตฌ์กฐ๋ฅผ๊ฐ€์ง€๊ณ ์žˆ์–ด์—ฌ๋Ÿฌ๋ถ„์•ผ์—์„œํ™œ๋ฐœํ•˜๊ฒŒ์‚ฌ์šฉ๋˜๊ณ ์žˆ๋‹ค.ํŠนํžˆ๊ธˆ์œต๋ถ„์•ผ์˜์‹œ๊ณ„์—ด๋ฐ์ดํ„ฐ์—์‘์šฉ๋˜์–ด๋‹ค์–‘ํ•œ์—ฐ๊ตฌ๊ฐ€์ง„ํ–‰๋˜๊ณ ์žˆ๋‹ค.๋ณธ์—ฐ๊ตฌ๋Š”HMM์ด๋ก ์„๊ตญ๋‚ด KOSPI200์ฃผ๊ฐ€์ง€์ˆ˜์™€๋”๋ถˆ์–ด NIKKEI225, HSI, S&P500, FTSE100๊ณผ๊ฐ™์€ํ•ด์™ธ์ฃผ๊ฐ€์ง€์ˆ˜์˜ˆ์ธก์—์ ์šฉํ•ด๋ณด๊ณ ์žํ•œ๋‹ค.๋˜ํ•œ,์ตœ๊ทผ์ธ๊ณต์ง€๋Šฅ๋ถ„์•ผ์˜๋ฐœ์ „์œผ๋กœ์ธํ•ด์ฃผ์‹๊ฐ€๊ฒฉ์˜ˆ์ธก์—๋นˆ๋ฒˆํ•˜๊ฒŒ์‚ฌ์šฉ๋˜๋Š”์„œํฌํŠธ๋ฒกํ„ฐํšŒ๊ท€(support vector regression, SVR)๊ฒฐ๊ณผ์™€์–ด๋–ค์ฐจ์ด๊ฐ€์žˆ๋Š”์ง€๋น„๊ตํ•˜์—ฌ์‚ดํŽด๋ณด๊ณ ์žํ•œ๋‹ค.

์ฃผ์š”์šฉ์–ด:์„œํฌํŠธ๋ฒกํ„ฐํšŒ๊ท€,์€๋‹‰๋งˆ๋ฅด์ฝ”ํ”„๋ชจ๋ธ,์ฃผ๊ฐ€์ง€์ˆ˜์˜ˆ์ธก,์ฝ”์Šคํ”ผ200์ง€์ˆ˜,ํ•ด์™ธ์ฃผ๊ฐ€์ง€์ˆ˜

์ด๋…ผ๋ฌธ์€ 2020๋…„๋„์ค‘์•™๋Œ€ํ•™๊ต์—ฐ๊ตฌ์žฅํ•™๊ธฐ๊ธˆ์ง€์›์—์˜ํ•œ๊ฒƒ์ž„.1๊ต์‹ ์ €์ž: (06974)์„œ์šธ์‹œ๋™์ž‘๊ตฌํ‘์„๋กœ 84,์ค‘์•™๋Œ€ํ•™๊ต๊ฒฝ์˜๊ฒฝ์ œ๋Œ€ํ•™์‘์šฉํ†ต๊ณ„ํ•™๊ณผ. E-mail: [email protected]