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. 2026 Feb 6;15:209. [Version 1] doi: 10.12688/f1000research.174407.1

Table 2. Results of the unit root test for stationary by test (PP) at level and first difference.

PP Stationary of search variables time series at the original level
Variables Y X1 X2 X3 X4
With constant t-Statistic -2.2502 -2.8115 -2.9942 -1.3723 -3.1484
Prob. 0.1908 0.1614 0.0399 0.5915 0.0272
Result n0 n0 ** n0 **
With Constant & Trend t-Statistic -2.7100 -3.3389 -2.9850 -2.0797 -3.2467
Prob. 0.2358 0.2678 0.1432 0.5484 0.0833
Result n0 n0 n0 n0 *
Without Constant & Trend t-Statistic -2.2597 -3.0593 -3.0065 -1.2434 -3.0890
Prob. 0.3239 0.1326 0.0031 0.1947 0.0024
Result n0 n0 *** n0 ***
Stationary of search variables time series at the First difference
Variables d(Y) d(X1) d(X2) d(X3) d(X4)
With constant t-Statistic -5.0706 -4.9499 -4.3532 -4.9004 -4.8449
Prob. 0.0001 0.0001 0.0008 0.0001 0.0001
With Constant & Trend Result *** *** *** *** ***
t-Statistic -5.0500 -4.9223 -4.3108 -4.8617 -4.8110
Prob. 0.0005 0.0007 0.0052 0.0009 0.0011
Result *** *** *** *** ***
Without Constant & Trend t-Statistic -5.0968 -4.9906 -4.3704 -4.9095 -4.8748
Prob. 0.0000 0.0000 0.0000 0.0000 0.0000
Result *** *** *** *** ***

Source: Prepared by the researchers based on the outputs of the statistical program (Eviews10).

- The sign (*) indicates that it is significant at the level of (10%), the sign (**) means its significance at the level of (5%), and the sign (***) means that it is significant at the level of (1%) respectively.

- n0: It indicates that it is insignificant.