The purpose of the present meta-analysis is to the investigate the overall effectiveness of L2 vocabulary instruction and to find the moderator variables affecting its effectiveness. By defining a rigorous inclusion and exclusion criteria, a total number of 16 primary studies (N = 1008), 7 published and 9 Ph.D. dissertations, were included. Under Random-Effects Model, the overall effect size of (d = 0.80) was observed. After conducting Q test of heterogeneity, a number of moderator variables were examined; context of instruction, publication type, age and L2 learners’ proficiency level. It was found that (a) studies conducted in foreign language contexts generated larger effect sizes than ones conducted in SL contexts.(b)intermediated learners show a larger effect size than advanced and elementary students. (c) child learners were better than adult learners in Learning L2 vocabulary. (d) Published studies generated larger effect size than doctoral dissertations. (e) employing “posters” for teaching L2 vocabulary items generated higher effect size than reading activities, CALL, and songs. (f) abstract words generated higher effect size than concrete ones. Possible explanations of the findings are discussed with regard to the similar meta-analyses in the field and directions for future research are proposed.

中文翻译：

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二语词汇教学的有效性：荟萃分析

本荟萃分析的目的是研究L2词汇教学的整体有效性，并找到影响其有效性的主持人变量。通过定义严格的纳入和排除标准，总共进行了16项基础研究（N = 1008），7项公开研究和9项博士学位。论文，包括在内。在随机效应模型下，观察到总体效应大小为（d = 0.80）。在进行异质性的Q检验后，检查了许多主持人变量。教学内容，出版物类型，年龄和二语学习者的熟练程度。研究发现（a）在外语环境下进行的研究产生的效果要比在SL环境下进行的研究要大。（b）中介学习者的效果要比高级和基础学生更大。（c）在学习第二语言词汇方面，儿童学习者比成人学习者要好。（d）已发表的研究产生的影响比博士学位论文更大。（e）雇用“海报”教授第二级词汇所产生的效果要比阅读活动，打电话和听歌高。（f）抽象词比具体词产生更大的效果。关于该领域类似的荟萃分析，讨论了对发现的可能解释，并提出了未来研究的方向。