RT Journal
A1 Mekary RA, Ding EL
T1 ANalysis of television viewing and physical activity using time substitution models
JF Archives of Internal Medicine
JO Archives of Internal Medicine
YR 2010
FD July 12
VO 170
IS 13
SP 1173
OP 1174
DO 10.1001/archinternmed.2010.210
UL http://dx.doi.org/10.1001/archinternmed.2010.210
AB 
Television (TV) watching time poses unique challenges in analysis. Recently, Otten at al1 described the effects of reducing TV viewing time on energy intake and expenditure in overweight and obese adults in a randomized controlled trial. Although a reduction in TV viewing produced a significant increase in total daily energy expenditure among those randomized to TV restriction compared with the control group, the authors also found a nonsignificant decrease in energy intake in both groups. However, the analysis of TV viewing time was carried out using multivariate models that did not account for effects of varying time displacement and relative time substitution, nor did it control for the confounding effect of total activity time. An analysis of reducing TV watching time without considering these issues may lead to bias and incomplete interpretation of the effects of decreasing TV watching time.2