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A completely randomised design, commonly abbreviated as CRD, contain two factors: experimental units and treatments with a completely unstructured experiment (i.e. no grouping for the factors). CRD is sufficiently characterised by the number of units, $$n$$, and the number of treatment, $$t$$. Instead of $$n$$, you ccan parameterise the design with the number of replications, $$r$$; in which case, you can derive $$n = rt$$. The later parameterisation means that the design will be balanced while the former does not guarantee that the design is balanced.

You can call on menu_crd() to see the code in the terms of the fundamental system. If you omit the argument values, then a random parameterisation will be selected for you. You can find more details about the design in the documentation (?menu_crd).

menu_crd()
design("Completely Randomised Design") %>%
set_units(unit = 23) %>%
set_trts(trt = 10) %>%
allot_trts(trt ~ unit) %>%
assign_trts("random", seed = 679) %>%
serve_table()

If you want to generate the design table, then you can use the takeout() function parsing the named design object created by the set of menu_ functions. If you don’t select any menu then the takeout() function will automatically select a random menu for you. You can find the list of available named experimental designs by calling on scan_menu(). For now, let’s “takeout” the completely randomised design with 5 treatments and 30 experimental units.

crd <- takeout(menu_crd(t = 5, n = 30, seed = 1), )
crd
design("Completely Randomised Design") %>%
set_units(unit = 30) %>%
set_trts(trt = 5) %>%
allot_trts(trt ~ unit) %>%
assign_trts("random", seed = 1) %>%
serve_table()

# Completely Randomised Design
# An edibble: 30 x 2
unit      trt
* <unit(30)> <trt(5)>
1     unit1      trt1
2     unit2      trt2
3     unit3      trt5
4     unit4      trt2
5     unit5      trt1
6     unit6      trt1
7     unit7      trt3
8     unit8      trt5
9     unit9      trt4
10     unit10     trt3
# … with 20 more rows

A design table generated by takeout() is an object with a special class of edbl_table. When you print a takeout object, a table will be displayed like a typical edbl_table object but the recipe code will also be displayed prior to the table.

You can quickly plot the design using the autoplot() in the deggust package.

autoplot(crd)