"小样本连续研究法" can be translated into English as "small-sample continuous research method" or "method of continuous research with small samples".
Both translations convey the key components of the original term:
"小样本" (small sample) is translated as "small-sample" or "with small samples,"
"连续研究法" (continuous research method) is translated as "continuous research method."
The choice between the two may depend on the context and the desired emphasis in the sentence.