The UK Feb KM unusually contains the results of the Kingdom News 37 & Convention invitation campaigns (they don't normally make the information public).
Convention invitation - 515 slips returned , "over 60%" requesting bible studies.
KN37 (to end of Nov , so somewhat incomplete) - 311 slips returned , 185 studies requested.
The report is spun so that "You will be delighted to learn the results" and "Jehovah has clearly blessed your hard work".
I can't help feeling that these results are very poor , though doubtless a devout JW would say that if only one study resulted , then that would be a fine result. A typical direct mail campaign would hope to elicit a 1% return at worst - presumably a leaflet drop where the leaflet was personally delivered to the householder would be higher. Assuming 10 million tracts were issued , this represents a 0.005% response rate. Put another way , if we assume that each tract cost 5p to produce & distribute (most of the expense falling on the publisher) , to generate each response cost £5000. No commercial company could afford this kind of feedback rate -the campiagn would be stopped immediately and the marketing staff would be sacked.
In my experience , even the quoted response rate should be taken with a pinch of salt. I travelled 30 miles once to "follow up" a slip that had been posted to the WTS , only to find that it was done for a laugh by someone who had put his work colleagues name & address on a slip.
Is it worth it? Clearly the WTS thinks so , having started a Memorial tract campaign. Perhaps also , they tacitly acknowledge that the prime purpose of the preaching work is to "keep the brothers together". In the same KM , there is a push to get 12,500 auxiliary pioneers in the spring , and the usual 90 year old sister is quoted as an example. I paraphrase - "I wanted to work in my garden , but I was encouraged to pioneer" , she declares. The result? "I felt so closer to my brothers or sisters". Not "I started loads of studies."