This allowed analyzing the possible abnormal return
in different windows.
A hedge portfolio long (short) in low (high) accrual firms consisting of only small firms earns an insignificant abnormal return
, averaging 10.7 percent, which is not significantly different from the 7.1 and 8.1 percent hedge portfolio returns of large firms and medium-sized firms, respectively.
where [mathematical expression not reproducible] is the cumulative abnormal return
of share i during the event window [[[tau].sub.1]; [[tau].sub.2]], [R.sub.i,t] is the realized return of stock i on day t (1), [R.sub.M,t] is the return of the benchmark index of sector i, [[??].sub.i] and [[??].sub.i] are the regression estimates from an ordinary least squares (OLS) regression for 105 trading day estimation period until t = -10.
They construct portfolios of firms that had few textual changes in quarter-to-quarter reports and firms that had many changes, and find that portfolios that were long "non-changers" and short "changers" earned a statistically significant value-weighted abnormal return
of between 34 and 58 basis points per month--between 4 and 7 percent per year--over the following year.
Table 3 presents abnormal returns
over various event windows using the market-adjusted returns method (Brown and Warner, 1985), which is the daily abnormal return
calculated as the firm-specific return minus the CRSP value-weighted market return.
As a result, we are able to speculate that the abnormal return
was due to the event, i.e., the IOC announcement increased or decreased the future profitability of companies in those countries.
The difference between the actual return and the expected return on a given period is the abnormal return
The dependent variable is the cumulative average abnormal return
(CAAR) surrounding the date of each announcement in the sample.
Based on the market model, abnormal monthly returns were calculated using both the buy-and-hold return and cumulative abnormal return
methods for each firm.
Cumulative average abnormal return
in three day window period surrounding the date of recommendation is 1.41 per cent and they further observed that these returns increase gradually from 3 to 4 days prior and reach a peak return on the date of recommendation.
(9.) The t-statistics that measure whether the Cumulative Abnormal Return
is significantly different from zero over the event period window (t = l to t = k) are calculated using the dependence adjustment method as described by Brown and Warner (1985), with a holdout period from r = -30 to [??] is the variance of the abnormal return
computed over the holdout period, M is the number of days in the event period, and A[R.sub.t] is the abnormal return
on day t.
The abnormal return
of stock i on day t is the empirical difference between the observed return and the expected return during the event window: