PURPOSE The main purpose of this research was to examine the longitudinal measurement invariance of the Satisfaction With Life Scale (SWLS) in adolescence. METHOD The sample was composed by 484 adolescents from Spain, 46.7% were males. All participants belonged to six academic levels from Grade 7 to Grade 12, and answered the questionnaires at two different times: at the beginning (Mage1 = 14.95, SD1 = 1.81) and at the end of the school year (Mage2 = 15.61, SD2 = 1.81). The reliability of the scale was obtained through Cronbach's alpha, Guttman lambda, and MacDonald's Omega total. The multiple group confirmatory factor analysis (MGCFA) was used to examine the fit of the unifactorial model to data and to test the measurement of longitudinal invariance of the scale across two time points (at the beginning T1, and the end T2, of the academic year), and the time points and groups (gender and age). RESULTS The values of the single-factor SWLS structure were T1 (CFI1 = 1.000, TLI1 = .997, RMSEA1 = .080, and SRMR1 = .028), and T2 (CFI2 = .997, TLI2 = .995, RMSEA2 = .032, and SRMR2 = .034). On the other hand, values of the reliability and composite reliability when analyzing both time points together as well as separately were as follows: Cronbach's alpha = .86, Guttman's lambda = .84, McDonald's Omega total = .89. Results confirmed the longitudinal invariance of SWLS. The differences in gender and age were not significant and the small differences across time points showed that the means of the latent factor remained the same over time in both variables. CONCLUSION The present study confirmed the single-factor structure of the SWLS in Spanish adolescents, as well as a good reliability and composite reliability. The full longitudinal measurement invariance was also found and there were negligible differences across time points considering gender and age. If these findings are further replicated, the scale could be used to compare the life satisfaction across two time points considering different age and gender groups.

中文翻译：

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青春期生活满意度的纵向测量不变性。

目的本研究的主要目的是检验青春期对生活满意度的满意程度（SWLS）的纵向测量不变性。方法该样本由西班牙的484名青少年组成，其中男性占46.7％。从7年级到12年级，所有参与者都属于六个学术级别，并在两个不同的时间回答了问卷：在开始时（Mage1 = 14.95，SD1 = 1.81）和在学年末（Mage2 = 15.61，SD2 = 1.81）。量表的可靠性是通过Cronbach's alpha，Guttman lambda和MacDonald's Omega总数获得的。多组验证性因子分析（MGCFA）用于检查单因子模型与数据的拟合度，并测试两个时间点（在开始时间T1和结束时间T2，学年），时间点和组（性别和年龄）。结果单因素SWLS结构的值为T1（CFI1 = 1.000，TLI1 = .997，RMSEA1 = .080，SRMR1 = .028）和T2（CFI2 = .997，TLI2 = .995，RMSEA2 =。 032，而SRMR2 = .034）。另一方面，分别分析两个时间点时的可靠性和综合可靠性值如下：Cronbach's alpha = .86，Guttman lambda = .84，McDonald's Omega total = .89。结果证实了SWLS的纵向不变性。性别和年龄的差异不显着，跨时间点的细微差异表明，在两个变量中，潜在因素的均值随时间保持不变。结论本研究证实了西班牙青少年中SWLS的单因素结构，以及良好的可靠性和复合可靠性。还发现了完整的纵向测量不变性，考虑到性别和年龄，各个时间点之间的差异可以忽略不计。如果进一步复制这些发现，可以使用该量表比较考虑不同年龄和性别组的两个时间点的生活满意度。