South Korea Consumer Sentiment Index

KRCSI is the raw consumer-sentiment composite index recorded each month, carried through without transformation. It expresses the level of household confidence in current and prospective economic conditions as a single standardized figure benchmarked to a long-run reference value of 100, where readings above that mark denote optimism and readings below it pessimism.

The measure rests on the behavioral premise that consumers' attitudes and expectations are themselves observable and economically consequential determinants of spending (Katona 1951).

Its raw material is a qualitative business-tendency survey in which respondents report only whether their situation and outlook are better, about the same, or worse. This up-same-down design was formalized by Anderson (1952), and those trichotomous replies are condensed into a continuous figure by balance and probability reasoning (Theil 1952; Carlson and Parkin 1975).

Pooling several such question-level balances into one headline follows the composite and diffusion-index tradition of Moore (1961). This exercise sits within the program of cyclical-indicator measurement begun by Mitchell and Burns (1938) and Burns and Mitchell (1946), and it was later recast as a latent common factor of comoving monthly series (Stock and Watson 1991).

The series therefore belongs to the family of attitudinal current-conditions gauges, whose construction and meaning have been reviewed across the literature (Zarnowitz 1992; Nardo 2003; Ludvigson 2004).

KRED applies no transformation to KRCSI, neither rescaling, deflation, seasonal adjustment, smoothing, nor annualizing, and stores the published monthly figure exactly as received. The methodology to describe is therefore limited to the survey-and-index basis by which such a figure comes to exist.

The starting point is a tendency survey of the Anderson (1952) type, in which households answer in qualitative up-same-down terms rather than reporting magnitudes. The theoretical link between the balance of replies and underlying conditions was first set out by Anderson (1952).

Converting those qualitative shares into a quantitative reading uses the balance and probability methods of Theil (1952) and Carlson and Parkin (1975). This family of quantification procedures was surveyed and compared by Nardo (2003).

The several question-level series are then merged into one composite by the diffusion and composite-index construction codified by Moore (1961) and operationalized for monthly real-time signaling by Shiskin (1961). This is an exercise in the indicator-selection program of Mitchell and Burns (1938), whose modern statistical form treats the headline as a single latent factor of comoving aggregates (Stock and Watson 1989, 1991).

Interpreting the resulting composite against the cycle draws on the turning-point and reference-cycle apparatus of Bry and Boschan (1971) and the synthesis of Zarnowitz (1992). The standing caution that such atheoretical measurement is not a structural model is the one stated by Koopmans (1947).

As an economic gauge, KRCSI is read as a timely summary of the household sector's perceived state of the economy. Katona (1951) envisaged this role when he argued that measured attitudes and expectations help drive consumption independently of current income.

Its standing as a coincident-to-leading read on activity follows from the cyclical-indicator framework of Mitchell and Burns (1938), Burns and Mitchell (1946), Moore (1961), and Shiskin (1961), and from the dynamic-factor reinterpretation of the state of the economy by Stock and Watson (1989).

Empirically, consumer sentiment carries independent forecasting content for household spending beyond what fundamentals explain (Carroll, Fuhrer, and Wilcox 1994; Ludvigson 2004). This property is what makes the series economically informative.

Because sentiment co-moves with labor-market perceptions, it is often read alongside the labor-force aggregates. Those aggregates rest on the operational definitions of the labor force (Hussmanns, Mehran, and Verma 1990) and the flow view of unemployment (Clark and Summers 1979), and the series is also read against the broader evaluation of the indicator approach (Zarnowitz 1992).

The series describes perceived conditions rather than furnishing a structural forecast. This interpretive limit was emphasized by Koopmans (1947).

In financial use, KRCSI serves as a high-frequency read on the consumer that markets monitor for early signals on discretionary demand. Its predictive content for spending was established by Carroll, Fuhrer, and Wilcox (1994) and reviewed by Ludvigson (2004).

Its appeal to practitioners is the same one that Katona (1951) identified. That is, survey-measured expectations move ahead of realized outlays and so carry information about the near-term path of consumption-sensitive earnings and credit.

Read as a cyclical indicator in the tradition of Moore (1961), Shiskin (1961), and Zarnowitz (1992), the series helps locate the economy relative to reference-cycle turning points. Those turning points are dated by the apparatus of Burns and Mitchell (1946) and Bry and Boschan (1971), and such placement matters for positioning across the cycle.

Because the headline is a quantified balance of qualitative replies, its movements must be read with the attendant measurement caveats (Theil 1952; Carlson and Parkin 1975; Nardo 2003). Those movements must further be interpreted within the single-factor representation of comoving activity (Stock and Watson 1991).

The series is a descriptive sentiment gauge rather than a tradable forecast.

KRCSI is a not-seasonally-adjusted monthly consumer-sentiment index, tested over 215 observations from 2008-07 to 2026-05 under a constant specification without trend, since the level fluctuates around a nonzero mean with no deterministic trend. The survey scale is bounded but never binds over the sample, so the standard and bounded-support unit-root nulls nearly coincide and no bounded correction is needed (Cavaliere and Xu 2014).

The augmented Dickey and Fuller (1979) test with the lag augmentation of Said and Dickey (1984) rejects a unit root at p = 0.0061, the Phillips and Perron (1988) test rejects more decisively at p = 0.0007, and the KPSS test does not reject stationarity at p > 0.10 (Kwiatkowski et al. 1992), so all three procedures concur on a clean I(0) classification. The DF-GLS escalation of Elliott, Rothenberg, and Stock (1996) is reserved for ambiguous readings and is not required here.

On the clean I(0) verdict the level is the stationary object, so its mean-break date is citable. The Bai and Perron (1998) procedure, computed by the algorithm of Bai and Perron (2003), identifies a single mean shift at 2018-08, read as a level movement of a stationary series rather than a stochastic-trend break (Perron 1989).

The index is not seasonally adjusted, and the seasonal battery is the designed diagnostic. The HEGY test rejects seasonal unit roots at p = 0.000 (Hylleberg et al. 1990) and the seasonal-dummy F test rejects at p = 0.041, so the seasonality present is deterministic rather than stochastic, consistent with the stationary-seasonality null of Canova and Hansen (1995) and the seasonal-analysis framework of Ghysels and Osborn (2001). The QS statistic on the differenced series does not reject at p = 0.7355, so no residual seasonal autocorrelation remains beyond the deterministic pattern. On the stationary level the Ljung and Box (1978) portmanteau rejects the no-autocorrelation null at p = 0.000 at both the lag-12 and lag-24 rungs, confirming the strong serial dependence expected of a persistent sentiment level.