面板单位根检验中，xtunitroot fisher  命令报告了四个统计量，判断是否存在单位根，主要关注哪个统计量呢？另外，如果在论文中报告 fisher  adf 检验结果，应该报告哪个变量？还是四个变量都报告呀？
附检验结果：

. xtunitroot fisher l_c, trend dfuller  lags(2) demean
Fisher-type unit-root test for l_c
Based on augmented Dickey-Fuller tests
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Ho: All panels contain unit roots           Number of panels  =     29
Ha: At least one panel is stationary        Number of periods =     20
AR parameter: Panel-specific                Asymptotics: T -> Infinity
Panel means:  Included
Time trend:   Included                      Cross-sectional means removed
Drift term:   Not included                  ADF regressions: 2 lags
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                                  Statistic      p-value
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Inverse chi-squared(58)   P        55.9605       0.5515
Inverse normal            Z         0.7753       0.7809
Inverse logit t(149)      L*        0.7790       0.7814
Modified inv. chi-squared Pm       -0.1894       0.5751
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P statistic requires number of panels to be finite.
Other statistics are suitable for finite or infinite number of panels.
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