  In this paper, we conduct a thorough investigation into the reasoning
capabilities of Large Language Models (LLMs), focusing specifically on the Open
Pretrained Transformers (OPT) models as a representative of such models. Our
study entails finetuning three different sizes of OPT on a carefully curated
reasoning corpus, resulting in two sets of finetuned models: OPT-R, finetuned
without explanations, and OPT-RE, finetuned with explanations. We then evaluate
all models on 57 out-of-domain tasks drawn from the SUPER-NATURALINSTRUCTIONS
benchmark, covering 26 distinct reasoning skills, utilizing three prompting
techniques. Through a comprehensive grid of 27 configurations and 6,156 test
evaluations, we investigate the dimensions of finetuning, prompting, and scale
to understand the role of explanations on different reasoning skills. Our
findings reveal that having explanations in the fewshot exemplar has no
significant impact on the model's performance when the model is finetuned,
while positively affecting the non-finetuned counterpart. Moreover, we observe
a slight yet consistent increase in classification accuracy as we incorporate
explanations during prompting and finetuning, respectively. Finally, we offer
insights on which skills benefit the most from incorporating explanations
during finetuning and prompting, such as Numerical (+20.4%) and Analogical
(+13.9%) reasoning, as well as skills that exhibit negligible or negative
effects.
