Draft lottery (1969)

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On December 1, 1969, the Selective Service System of the United States held a lottery to determine the order of draft (induction) into the U.S. Army for the Vietnam War.

Representative Alexander Pirnie (R-NY) drawing the first number.

1 Method
2 Consequences
3 Modification
4 References
5 External links

[edit] Method

The days of the year, represented by the numbers from 1 to 366 (including Leap Day), were written on slips of paper and the slips were placed in plastic capsules. The capsules were mixed in a shoebox and then dumped into a deep glass jar. Capsules were drawn from the jar one at a time.

The first day number drawn was 257 (September 14), so all registrants with that birthday were assigned lottery number 1. Men of draft age (those born between 1944 and 1950) whose birthday fell on the corresponding day of the year would all be drafted at the same time. The highest draft number called from the 1969 lottery was number 195 (September 24).

1969 draft lottery scatterplot. A scatterplot of the days of the year (horizontal axis) and their ranks (vertical axis) shows a noticeable absence of days in December with high ranks (later induction).

A secondary lottery was also held on the same day, to construct a random permutation of the 26 letters of the alphabet. For men born on a given day, the order of induction was determined by the rank of the first letters of their last, first, and middle names. [1]

The lottery was conducted again in 1970 (for those born in 1951), 1971 (1952) and 1972 (1953), although the 1972 lottery went unused as the draft itself was suspended in 1973. Lotteries were also conducted in 1973, 1974 and 1975 although the assigned numbers went unused.

[edit] Consequences

It was quickly noticed that draft ranks were not uniformly distributed over the year. In particular, birthdays in December had lower (earlier) draft ranks, on average, than birthdays in other months. This led to complaints that the lottery was not random as the legislation required. Analysis of the lottery method suggested that the procedure (mixing the capsules in the shoe box and dumping them into the jar) did not mix the capsules sufficiently;^{[citation needed]} however, the less-than-random lottery was allowed to stand. The lottery system was later modified to produce a more random result.

[edit] Modification

In the 1970 and subsequent draft lotteries, a different method was used. Scientists at the National Bureau of Standards randomly prepared 78 permutations of the numbers from 1 to 365, using random numbers selected from published sources.^[1]

From the 78 permutations, 25 were selected at random and translated to calendars using 1 = january 1, 365 = December 31, etc. The calendars were sealed into envelopes. 25 more permutations were selected and left untranslated and sealed into 25 more envelopes. The 50 envelopes were furnished to the Selective Service System.^[1]

On 29 June, an official picked one of the calendar envelopes and one of the permutation envelopes. The 365 days of the year were written down and placed into capsules and put in a drum in the order dictated by the contents of the calendar envelope. Similarly the numbers from 1 to 365 were written down and placed into capsules in the order dictated by the permutation in the permutation envelope.^[1]

On 1 July, the drawing date, one drum was rotated for an hour and the other for a half-hour (its rotating mechanism failed).^[1]

Pairs of capsules were then drawn, one from each drum. The first date out of the drum with the date capsules was September 16; the first number drawn from the drum with the numbers was 139. Thus men born on September 16th were drafted in 139th order. The 11th draws were the date July 9 and the number 1, so men born on July 9 were drafted first.^[1]

[edit] References

S.E. Fienberg. "Randomization and Social Affairs: The 1970 Draft Lottery". Science, volume 171, pages 255-261 (1971). (Cited by Starr as the "best and most comprehensive" article on the topic)
D.E. Rosenbaum. "Statisticians Charge Draft Lottery Was Not Random," New York Times, January 4, 1970, p. 66.
Selective Service System: History and Records [2]
Norton Starr. "Nonrandom Risk: The 1970 Draft Lottery". Journal of Statistics Education, volume 5, number 2 (1997). (Also available on-line: [3] Contains a lesson plan for statistics class using the 1970 and 1971 draft lottery data)