Variable action quincunx pinplate

A statistics teaching aid of the Quincunx type. The device includes a pinplate which has at least one movable row of pins. Shifting of the movable pinrow effectively increases or decreases the number of pinrows on the pinplate. By shifting the pinrow, an operator can alter the shape of the resulting distribution of balls.

FIELD OF THE INVENTION 
The invention is in the field of educational aids for the study of 
statistics. More specifically, the invention is a Quincunx apparatus that 
includes a modified pinplate that allows the operator to, in effect, vary 
the number of rows of pins. 
BACKGROUND OF THE INVENTION 
A number of visual aids are often employed in the teaching and study of 
statistics. These aids range from simple coins to computer generated 
curves and graphs. A common device specifically designed for statistical 
modeling is the Quincunx which was invented by Lord Francis Galton in the 
1870's. 
A Quincunx employs a funnel shaped conduit to direct a dropped ball 
downwardly into a pinplate. The pinplate includes a number of spaced rows 
of outwardly extending pins. Each pin is separated from its neighboring 
pin by a distance slightly greater than the diameter of the dropped ball. 
As the ball passes downwardly through the pinplate, it bounces off one pin 
in each row of pins. 
Each row of pins represents an independent disturbance or decision point. 
When the ball hits one of the pins, it can randomly fall to either the 
right or left side of the pin. Therefore, if the pinplate includes ten 
rows of pins, a dropped ball would make ten "choices" in direction before 
it left the pinplate. After passing through the last row of pins, the ball 
falls into a "stacking" area. 
The stacking area comprises a series of vertically extending receiving 
grooves or slots. As the dropped ball leaves the pinplate, it falls into 
the slot directly below its exit point from the pinplate. One or more 
ball-stops are located in the stacking area and function to stop the 
ball's downward progress. The dropped balls stack up atop the ball-stop(s) 
and thereby illustrate the distribution which results from the decision 
path of the balls through the pinplate. The ballstop(s) can be moved to a 
"release" position which allows the stacked balls to fall into a bottom 
reservoir. 
A Quincunx is often used to demonstrate process capabilities or stacking of 
tolerances. For example, if ten washers are to be stacked and each washer 
is picked at random from a supply having equal numbers of washers of two 
different sizes, there is a large range of possible stack heights. If the 
two sizes of washers are one-inch and two-inches respectively, and one 
happens to pick ten one-inch washers, the stack height will be ten inches. 
If only two-inch washers are picked, the stack height will be 20 inches., 
Most likely however, the final stack height will be between these 
extremes. If a large number of washers are picked, approximately one half 
will be of one size and the other half will be of the other size. For the 
above example, one would have the greatest probability of picking five, 
one-inch washers and five, two-inch washers. Therefore, the probable stack 
height would be fifteen inches. 
A Quincunx could be used to illustrate the above example. A single ball 
would be dropped from the conduit into a pinplate having ten rows of pins. 
Each row of pins represents one pick of a washer. If the ball falls to the 
right, this would represent choosing a two-inch washer. If the ball falls 
to the left, this represents a one-inch washer being chosen. 
Below the pinplate would be located ten groves or slots labeled "10" 
through "20" respectively with the leftmost groove being labeled "10". 
These grooves would represent the final stack height. 
Dropping a large number of balls into the pinplate would simulate an 
equally large number of attempts at stacking. The balls would stack up in 
the grooves and illustrate the distribution of probable stack heights. The 
balls collected in the grooves would eventually fall into a bell-shaped 
pattern called a "normal" or "Gausslan" distribution. In this example, the 
top of the curve would most likely be located in the groove marked "15" 
and this would indicate that the most probable stack height would be 15 
inches. 
The problem with the prior art Quincunx devices arises when it is desired 
to change the number of pinrows (rows of pins) used in the pinplate. If, 
for example, only five washers were to be picked, one would want a 
pinplate having only five rows of pins. The normal method of accomplishing 
this change is to replace the pinplate with another having the desired 
number of pinrows. This requires the user to have a supply of replacement 
pinplates that have different numbers of pinrows. 
The above solution, while workable, poses a number of problems. One is 
required to purchase and store the additional replacement pinplates. This 
is especially onerous when a large number of pinplates are needed. 
Replacing one pinplate with another is a time consuming procedure that is 
inconvenient during a teaching session. Also, due to the critical 
placement of the ball receiving slots below the gaps in the bottom pinrow, 
the pinplate is required to be an exact, tight fit. A major problem arises 
since pinplates and Quincunxes are commonly made from wood. The wood 
expands and contracts depending on such factors as wood type, grain 
pattern and the wood sealing materials that were used. Therefore, the 
manufacturing tolerances required for the pinplate and the Quincunx hole 
into which it fits are critical. These tolerances are extremely hard to 
meet and this sometimes leads to the pinplate being a poor fit and thereby 
being hard to remove without breakage of the plate or the Quincunx. 
Therefore, the present method of providing a measure of versatility to the 
Quincunx to illustrate changing conditions is unsatisfactory for most 
situations and effectively limits the use of the device. In addition, the 
manufacturing time and skill required to make the device is excessive. 
SUMMARY OFF THE INVENTION 
The instant invention is an improved Quincunx that is easy to use and far 
more versatile than previous devices of this type. The invention involves 
a modified pinplate that allows the operator to effectively change the 
number of pinrows without removing the pinplate. Since there is no need to 
remove the pinplate, the manufacture of the Quincunx is greatly 
simplified. The tight tolerances required by the prior art devices is 
eliminated. In addition, the overall cost of the device is lessened 
because one is no longer required to own and store a plurality of 
pinplates with different numbers of pinrows. Finally, the use of the 
Quincunx in a classroom environment is greatly enhanced since the operator 
can effectively change the number of pinrows in a matter of moments and 
thereby be able to quickly illustrate changed parameters.

DETAILED DESCRIPTION OF THE DRAWINGS 
Referring now to the drawings in greater detail, wherein like reference 
characters refer to like parts throughout the several figures, there is 
shown by the numeral 10 a Quincunx type of statistics teaching device. The 
device comprises a top ball reservoir 12, a movable funnel shaped conduit 
22 and a pinplate 26. Below the pinplate is the ball stacking area which 
comprises a row of vertically extending grooves 50. Located laterally 
across the grooves are a number of spring loaded ball-stops 32. At the 
bottom of the Quincunx, is a ball collection reservoir 52. A side passage 
54 connects the bottom ball reservoir 52 to the top ball reservoir 12. 
Between the top ball reservoir 12 and the conduit 22 there is a movable 
feeder member 14 that includes an exterior handle 16. The feeder member 
includes a plurality of slots 18 which are each sized to receive a ball 
from the upper reservoir. Below the feeder member is an entry orifice 20 
which allows one ball at a time to fall into the movable conduit 22. 
The rear wall of the conduit includes a rearwardly extending handle member 
(not shown) that is accessible from the rear of the device. The handle is 
horizontally movable and slides within slot 24. The handle is used to 
position the conduit over a desired region of the pinplate. 
Located below the conduit is the pinplate 26. The pinplate shown includes 
ten horizontal rows of pins. Each row of pins, or pinrow, includes a large 
number of pins that are spaced from each other by a distance that is 
greater than the diameter of the balls to be used in the device. The 
pinplate shown includes eight stationary pinrows 28 and two movable 
pinrows 30. 
FIG. 1 shows the movable pinrows in a first position in which their pins 
are staggered relative to the adjacent stationary rows of pins. 
FIGS. 2-4 show, in more detail, the Quincunx in the region of the pinplate. 
In FIG. 2, the movable pinrows 30 can be seen in their second position. As 
shown, the pins of the movable pinrows are in line with the pins of the 
stationary adjacent pinrows. By thus doing, the pins of the movable 
pinrows no longer interfere with the downward travel of a ball. 
As can be seen in FIG. 3, each movable pinrow comprises a base member 32 
which is slidably received within a groove 34 in the pinplate. Extending 
outwardly from an exterior surface of the base member are a plurality of 
pins 36. Extending rearwardly from the base member is a handle comprising 
a connecting shaft 38 and outer grip member 40. 
The connecting shaft is located within a horizontally extending slot 42. 
This location allows horizontal movement of the shaft. FIG. 3 shows a bolt 
44 being used for the connection shaft with the head of the bolt being 
received within the grip member. 
FIG. 4 shows a rear view of the pinplate. In this view, the two slots 42 
can be easily seen and an arrow is shown illustrating the allowed 
side-to-side movement. The slots are sized to allow the pinrow to move a 
distance equal to one-half of the pin spacing. The pinplate is attached to 
the main support board 46 of the device by four fasteners 48. Two indents 
50 are located above and below the pinplate to facilitate any required 
removal of the pinplate from the support board. 
Returning to FIG. 1, a plurality of grooves 50 are located beneath the 
pinplate. These grooves are fashioned by either a milling operation of the 
main support board or by adding long strips to the face of the support 
board to thereby make the sidewalls of the grooves. These grooves run 
between the pinplate 26 and lower reservoir 52. 
In order to stop the downward movement of the balls, a number of ball-stops 
32 are placed at intermediate locations in the grooves. Dropped balls 
stack up atop the ball-stops and thereby illustrate the final ball 
distribution after the balls have passed through the pinplate. 
Each of the ball-stops comprises a long member 56 having a plurality of 
slots 58 along its outer surface. The long member is slidably retained on 
the outer surface of the support board by a slot 60 which runs 
substantially the entire width of the device. Within the slot and located 
at the leftward end of the member is a biasing spring 62. 
Located on the right side of the device are a series of clamps 64 which are 
used to lock the ball-stop member in its leftwardmost position (note the 
locked top ball-stop 66). In this position, the slots 58 are aligned with 
the grooves and do not act to stop the downward progress of the balls. The 
clamps 64, when in their released position, allow their associated 
ball-stops to move to their rightmost position due to the action of the 
biasing springs 62 (note the bottom two ball-stops). In this position, the 
slots 58 are staggered from the grooves and thereby do not allow any 
downward movement of the balls. 
Once the balls are allowed past the ball stops, they freely fall into the 
bottom reservoir 52. 
In operation, one would start with all of the balls in the upper reservoir 
12. If one wanted to use a pinplate having ten pinrows, the movable pin 
rows would be positioned as shown in FIG. 1. If only six pinrows were 
required, the movable pin rows would be positioned as shown in FIG. 2. A 
single movable pinrow can be moved to obtain a pinplate having, in effect, 
eight rows of pins. 
The feeder member 14 would be shifted from right to left to feed balls into 
the orifice 20. From there, the balls would fall into the conduit 22 where 
they would be directed into the top of the pinplate. The balls would then 
bounce from pinrow to pinrow as they fall downwardly due to the force of 
gravity. As each ball hits a pin, the ball would randomly fall to either 
the right or left. Upon exiting the pinplate, each ball would enter one of 
the grooves 50. 
As shown in FIG. 1, the balls would collect above one of the ball-stops and 
thereby illustrate a normal distribution based on the above random right 
or left shifts in direction. 
Finally, the balls would be allowed to fall into the bottom reservoir 52. 
The balls can be returned to the top reservoir by appropriate shifting of 
the device to allow the balls to travel through passageway 54. 
It should be noted that the number of shiftable pinrows can be more or less 
than shown. For the pictured device, five movable pinrows could have been 
used. By alternating the stationary and movable pinrows, the device can 
have, in effect, zero to ten pinrows. Alternating the pinrows 
(movable/stationary) enables the operator to reduce or increase the 
effective pinrows by two by shifting only a single movable pinrow. 
The embodiment disclosed herein has been discussed for the purpose of 
familiarizing the reader with the novel aspects of the invention. Although 
a preferred embodiment of the invention has been shown and described, many 
changes, modifications and substitutions may be made by one having 
ordinary skill in the art without necessarily departing from the spirit 
and scope of the invention.