| Re: Chance to hit (Heavy) minefields much lower than documented? |
Wed, 15 August 2018 03:49   |
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 mrvan |
 | Officer Cadet 1st Year |
Messages: 220
Registered: May 2014 | |
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Thanks for the reply. This is approximately what I'm doing. You didn't really think I made the 50 trials by hand, right?  . Doing it with just one scout per mine field to get actual odds is a good idea though.
What is much easier than analysing the m1 file is getting a fleet report and inspecting that. My setup is here: https://gist.github.com/vanatteveldt/1517f8d38c0e818af2e062f 50dcabb6e (in R, using wine to call stars!)
I'll do a test run with multiple field locations and a single scout per field, that should give results pretty quickly.
First results. Setup: 4 heavy fields around player #2's HW, each 100 mines, more or less random directions. 1 scout set to fly through the center of each field at W9. https://imgur.com/a/XsF0Lop
Ran 500 iterations, recorded survival of each ship after each run.
Expected results: chance to hit 45.62% [from STARS.XLS; check: W9 is 3 above safe, so 97% chance of missing. 10 radius field, so 20ly travel, chance to hit = 1 - (.97**20) = 0.4562]
Actual results:
name chance_hit
<chr> <dbl>
1 Bulushi Test NE 0.190
2 Bulushi Test NW 0.178
3 Bulushi Test SE 0.316
4 Bulushi Test SW 0.264
[n=500 iterations, 1 trial per iteration per direction, chance_hit = 1 - (#survivors / 500) ]
So, chance to hit is 19 - 32%, rather than expected 45%.
Edit2: Second batch of results, for only cardinal / true diagonal directions. Same setup, so same expected chance to hit:
name chance_hit
Bulushi Test E 0.382
Bulushi Test N 0.
Bulushi Test NW 0.192
Bulushi Test SW 0.326
[n=500 iterations, 1 trial per iteration per direction, chance_hit = 1 - (#survivors / 500) ]
So, moving N gives a 0% chance to hit (unsurprising given NS mine travel bug, although it was unclear to me whether that also affected heavy mines). Moving straight east gives a relatively high chance to hit, although it is still substantially less than 46%. I'll try with more iterations when I get home. Going diagonal NW gives low chance to hit, SW medium
Tentative conclusion: chance to hit heavy minefields is lower than reported and depends on direction of travel or some unknown parameter. Which is kinda weird?
Could the results be chance? Chance of getting less than 40% hits (200 / 500) is 0.005%, chance of getting less than 20% hits (100/500) is < 0.000001 (https://stattrek.com/online-calculator/binomial.aspx)
These results don't make any sense to me. With 500 iterations the difference between e.g. .33 and .38 could well be chance, 95% confidence interval around .326 is .285 - .369; but difference between .382 and .192 doesn't seem likely to arise by chance. I'll run 10k iterations tonight, that should reduce confidence intervals to +/- 1%. [http://statpages.info/confint.html]
I'll also test with normal mine fields and with larger heavy fields, see if the pattern is the same. What other parameters could be relevant?
Anyone with a possible explanation for these results?
Links to scenario setups:
- scenario with random locations: https://www.dropbox.com/sh/twhdewil9oop3lk/AAAcXbSJTKJPz5_SF 3XTVQnpa?dl=0
- scenario with cardinal/diagonal relations: https://www.dropbox.com/sh/twhdewil9oop3lk/AAAcXbSJTKJPz5_SF 3XTVQnpa?dl=0
...
[Updated on: Wed, 15 August 2018 06:36] Report message to a moderator
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