Given the task definition and input, reply with output. Given a sentence in Igbo language, translate the sentence to English language keeping the meaning of the original sentence intact

Igbo sentence: Ndi na-eri na oge atumatu na Blumenstock, Cadamuro, and On (2015) na-ezo ihe na-agbanwe na-eri-eri nke onye z nnyocha e mere-na anaghi agunye ofu-akwu ugw di ka ndi na-eri cha na hazie oku data.
The cost and time estimates in Blumenstock, Cadamuro, and On (2015) refer more to variable costthe cost of one additional surveyand do not include fixed costs such as the cost to clean and process the call data.