Co-procurement: making the most of collaborative procurement

Figures & data

Figure 1. Supply and demand network with intermediate nodes.

Figure 2. An example of buyers connections.

Figure 3. Graphic illustration of Dutch Food Valley.

Figure 4. Network structure.

Table 1. Purchasing price and ordering cost per supplier.

Supplier	Purchasing price	Ordering cost
1	4.2	250
2	3.8	260
3	3.8	230
4	3.6	240
5	3.6	260
6	4.4	240
7	4.1	280
8	4	220

Table 2. Demand for each buyer at each period.

	Time period
Buyer	1	2	3	4	5	6
12	980	1000	1020	1020	1040	1060
13	1070	960	1120	1130	1140	1150
14	1020	1020	1080	840	1110	1120
15	970	960	970	970	1000	1020
16	1010	970	1060	1010	1080	1100
17	1010	1040	1090	1080	1100	1110

Table 3. Relevant distances (per kilometre) between the different nodes in the network.

(i,j)	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17
1	–	–	–	–	–	–	–	–	215	228	227	211	228	239	230	234	223
2	–	–	–	–	–	–	–	–	89.5	109	101	85	102	113	104	108	97
3	–	–	–	–	–	–	–	–	107	112	111	113	112	115	116	118	107
4	–	–	–	–	–	–	–	–	48	53.4	52	54	53.2	56	55	60	48
5	–	–	–	–	–	–	–	–	94.5	96	116	90	90	91	117	113	117
6	–	–	–	–	–	–	–	–	71	53	53	68	64	55	56	61	48
7	–	–	–	–	–	–	–	–	101	82.6	82.7	98	93.5	85	86	90.7	68.3
8	–	–	–	–	–	–	–	–	128	123	108	134	129	126	111	112	88
9	–	–	–	–	–	–	–	–	–	15.3	24.8	7.1	11.2	18.3	25.6	21.3	33.8
10	–	–	–	–	–	–	–	–	15.3	–	19.8	21.8	4.7	5.2	18	16.3	28.8
11	–	–	–	–	–	–	–	–	24.8	19.8	–	31.4	25.8	23.4	6.7	8.7	11.3
12	–	–	–	–	–	–	–	–	7.1	21.8	31.4	–	14	27	32.2	27.8	40.3
13	–	–	–	–	–	–	–	–	11.2	4.7	25.8	14	–	6.4	24.3	20	32.5
14	–	–	–	–	–	–	–	–	18.3	5.2	23.4	27	6.4	–	22	19.3	31.8
15	–	–	–	–	–	–	–	–	25.6	18	6.7	32.2	24.3	22	–	8.5	16.6
16	–	–	–	–	–	–	–	–	21.3	16.3	8.7	27.8	20	19.3	8.5	–	12.5
17	–	–	–	–	–	–	–	–	33.8	28.8	11.3	40.3	32.5	31.8	16.6	12.5	–

Table 4. Replenishment decisions for buyer 15.

	$X_{5,15,m}^t$
Time Period	$m=1$	$m=2$	$H_{15}^t$	$B_{15}^t$
1	970	0	0	0
2	960	0	0	0
3	970	0	0	0
4	990	0	20	0
5	1000	0	20	0
6	1000	0	0	0

Table 5. Replenishment decisions for buyer 16.

	$X_{3,16,m}^t$
Time period	$m=1$	$m=2$	$H_{16}^t$	$B_{16}^t$
1	1000	0	0	10
2	980	0	0	0
3	0	1070	10	0
4	1000	0	0	0
5	0	1180	100	0
6	1000	0	0	0

Table 6. Costs per buyer.

Buyer	Total cost	Purchasing cost	Ordering cost	Holding cost	Transportation cost	Backordering penalty cost
12	26,236	22,032	1440	120	2644	0
13	28,186	23,652	1440	0	3094	0
14	27,607	21,665	1560	406	3976	0
15	26,437	20,615	1560	52	4210	0
16	29,640	29,640	1380	165	4948	96
17	30,235	30,235	1380	432	4552	80
Sum	168,341	147,839	8760	1175	23,424	176

Figure 5. Network flow for buyers 15 and 16.

Table 7. Cost components.

	Total cost	Purchasing cost	Ordering cost	Holding cost	Transportation cost	Backordering penalty cost	Transaction cost
Value	153,639	136,698	4150	385	10,504	102	1800
Reduction	14,703	11,141	4610	790	12,920	74	–

Table 8. Costs per buyer.

Buyer	Total cost	Savings from collaboration (%)
12	23,926.7	8.6
13	25,725.63	8.7
14	25,191.48	8.75
15	24,112.12	8.8
16	27,066.98	8.7
17	27,615.89	8.65
Sum	153,638.8	8.7

Figure 6. Comparison of costs in collaborative and non-collaborative setting.

Table 9. Sensitivity analysis on transaction cost.

Changes (%)	Collaboration size	Total cost
−100	6	147,314 (−4.2%)
−50	5	150,110 (−2.29%)
0	4	153,639
+50	4	154,539 (+58%)
+100	3	158,079 (+2.88%)
+150	2	161,701 (+5.24%)
+200	2	162,601 (+5.83%)
+250	2	163,501 (+6.41%)
+300	1	168,341 (+9.6%)

Figure 7. Sensitivity analysis on transaction cost.