The stand-alone videoconferencing equipment used in most studies could be very costly, and although prices have come down over the past decade, expensive tele-presence units with multiple screens and peripheral devices are now being marketed as new generation products.
In deglycosylation experiments 70 μg of jejunal homogenates were incubated at 37°C in the presence (5000 units) or in the absence of endoglycosidase Hf (New England BioLabs), according to the manufacturer's instructions.
Another important issue is the potential presence of unit roots in the variables.
In the presence of unit roots, estimating Eq. (1) with ordinary least squares would result in spurious coefficients.
Based on the result shown in Table 4, we rejected the null hypothesis of the presence of unit root in the residual.
The ADF test has a null hypothesis of the presence of unit roots, which is not rejected for the two Google time series but is rejected for the suicide time series.
To test for stationarity and the presence of unit roots, we use the Augmented Dickey-Fuller (ADF) test [62] and the KPSS test [63] with a maximum lag of three months.
We tested for the presence of unit roots (Table 2) following the procedures provided by Phillips and Perron (1988) hereafter P-P; and Dickey and Fuller (1979) hereafter D-F.
The authors studied the system dynamics using a time-series approach by testing for the presence of unit roots and using the Johansen approach to study long-term equilibrium.
Formal statistical testing for the presence of unit roots in time series was conducted using the Dickey-Fuller Test [ 30].
In assessing entry 10 ("Was the study apparently free of other risks of bias?"), it is important to pay extra attention to the presence of unit-of-analysis errors.
