Selection from the list of topics

Estimates and standard error of the estimates

The results published in the NFI tables are estimates for variables in the Swiss forest (population parameters) whose true values are not known and must therefore be extrapolated (estimated) from the NFI sample data.

The extrapolations carry uncertainties. However, the accuracy of the extrapolations can be reliably estimated from the NFI sample, which is designed to be a random sample. To this end, all NFI tables include a second figure in addition to the estimate itself, namely the standard error of the estimate.

In most tables the percent standard error is reported (±%), but the absolute standard error (±) is also reported occasionally, especially for estimated percentages. The relationship between absolute and percent standard error is as follows:

percent standard error = absolute standard error / estimate × 100

absolute standard error = percent standard error × estimate / 100

Information on the forest road network is based on a full survey of all forest roads. In this case, there is no need to specify a standard error because there is no uncertainty caused by sampling.

Confidence interval of the estimate

With the estimate and the standard error of the estimate, the limits of the so-called confidence interval of the estimate can be calculated as:

lower limit = estimate – tQ × absolute standard error

upper limit = estimate + tQ × absolute standard error

If the simple standard error is used for the calculation (tQ = 1), then the 68% confidence interval is formed. In this case, the true value of the population parameter has a 68% probability of lying within this confidence interval of the estimate. If the double standard error is used (tQ = 2), then there is a 95% probability that the true value lies within this 95% confidence interval.

Significance of the estimate

The confidence interval can be used to statistically test whether the estimated population parameter is larger or smaller than a specific reference or target value, or whether two estimated population parameters truly differ (in the real population). For practical applications, proceed as follows: if a reference value lies outside the confidence interval, the estimated population value can be interpreted as being significantly different from it; if it lies within the confidence interval, the difference between the estimated population parameter and the reference value can be interpreted as random or not significant. When two population parameters are compared, they can be interpreted as differing significantly if their confidence intervals do not overlap.

Dealing with missing values

When calculating a results table, data are not always available for all combinations of characteristics^* of the classification variables and regional demarcation applied. In most cases, this indicates that the attribute estimated with the respective target variable does not occur or occurs only very rarely. Usually, the value 0 is used (imputed). However, as this value is not based on direct measurements, the associated standard error is represented with a full stop [.]. If the imputed value of 0 is referred to in the calculation, e.g. in the case of percentages or certain change estimates, no value can be entered. In this case, the estimated value and standard error are both represented with a full stop [.].

For example, no Arolla pines have been found and measured in the Swiss Plateau to date (growing stock of Arolla pines by production region). The values can be assumed to be missing because Arolla pine does not occur in the Swiss Plateau and therefore the growing stock there must be 0.

^* e.g. ‘Arolla pine’ characteristic of the classification variable ‘tree species’ and ‘Swiss plateau’ characteristic of the ‘regional demarcation’

Changes

There are two types of changes in the NFI:

The first type involves specific target variables relating to components of change, such as increment, fellings, mortality and losses. These target variables are only available for two consecutive inventory cycles, e.g. NFI3–NFI4. In the evaluation of components of change, the classification variable characteristic of the second inventory cycle is assigned to the first inventory cycle. These evaluations therefore do not take into account potential changes in a classification variable characteristic from the earlier to the later inventory (e.g. from private to public ownership).

With the second type of change, the difference in target variables, such as number of stems, growing stock or forest area, is used to assess the change between two inventory cycles. Target variables are generally used to represent states, such as that in NFI4, but can also indicate the net change between any two inventory cycles, e.g. NFI1–NFI4. In evaluations of change using these target variables, the change in a classification variable characteristic is considered in the analysis. Consequently, one can detect, for example, that the forest area without shrub forest increased between the two inventory cycles. This only has an effect on classification variables whose characteristic (class) can actually change, e.g. the affiliation with a forest area or the tree condition.

NFI5
total number of stems with two most important forms of damages
altitude (in 200 m classes) · cause of damage to trees (10 classes)
regional demarcation: economic region
unit: 1000 n
evaluation area: accessible forest without shrub forest NFI1-NFI5
grid: 1.4 km grid, subgrids 1-5
state 2018/26
		economic region
		Western Jura		Eastern Jura		Western Plateau		Central Plateau		Eastern Plateau		Western Pre-Alps		Central Pre-Alps		Eastern Pre-Alps		Northwestern Alps		Central Alps		Northeastern Alps		Southwestern Alps		Southeastern Alps		Southern Alps		Switzerland
altitude (in 200 m classes)	cause of damage to trees (10 classes)	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%	1000 n	±%
n/a	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	rockfall	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	various	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	indeterminable	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	wood harvest	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	other human activity	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	weather	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	lying living trees	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	dead trees	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
>1800 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	0	.	0	.	0	.	0	.	0	.	0	.	69	100	0	.	730	52	0	.	0	.	5152	17	8599	14	1706	27	16256	10
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	7	100	7	100
	rockfall	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	294	28	74	45	217	67	584	29
	various	0	.	0	.	0	.	0	.	0	.	0	.	17	100	0	.	26	75	0	.	0	.	150	34	434	25	104	35	730	18
	indeterminable	0	.	0	.	0	.	0	.	0	.	0	.	66	100	0	.	292	49	0	.	0	.	1669	21	3413	16	523	30	5963	11
	wood harvest	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	79	53	20	76	0	.	100	45
	other human activity	0	.	0	.	0	.	0	.	0	.	0	.	14	100	0	.	9	100	0	.	0	.	293	46	44	47	47	86	406	35
	weather	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	290	30	192	32	119	67	601	22
	lying living trees	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	104	71	346	48	0	.	450	40
	dead trees	0	.	0	.	0	.	0	.	0	.	0	.	222	100	0	.	203	60	0	.	0	.	1673	22	2314	19	548	41	4959	13
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
1601-1800 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	0	.	0	.	0	.	0	.	0	.	764	51	2811	39	272	100	1719	27	262	48	1022	55	5791	19	6259	16	4120	19	23019	9
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	rockfall	0	.	0	.	0	.	0	.	0	.	32	71	163	53	0	.	118	63	0	.	0	.	138	39	275	39	101	43	828	21
	various	0	.	0	.	0	.	0	.	0	.	16	71	134	47	0	.	187	76	136	94	24	77	182	31	274	31	300	37	1254	20
	indeterminable	0	.	0	.	0	.	0	.	0	.	313	62	568	39	0	.	690	29	264	54	73	49	2152	19	2113	17	911	24	7085	10
	wood harvest	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	55	100	0	.	0	.	7	100	41	46	27	100	130	50
	other human activity	0	.	0	.	0	.	0	.	0	.	8	100	0	.	0	.	24	77	0	.	0	.	109	43	127	50	25	77	294	28
	weather	0	.	0	.	0	.	0	.	0	.	0	.	30	71	0	.	92	55	0	.	24	77	397	47	197	43	226	26	966	23
	lying living trees	0	.	0	.	0	.	0	.	0	.	0	.	79	92	22	100	0	.	0	.	0	.	49	54	0	.	0	.	151	53
	dead trees	0	.	0	.	0	.	0	.	0	.	180	59	613	51	127	100	948	39	93	58	96	54	1915	28	1120	21	525	28	5617	14
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
1401-1600 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	571	39	0	.	386	53	0	.	0	.	2195	37	2986	23	1513	36	3766	21	1556	37	826	36	5378	18	8388	15	5943	19	33509	7
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	rockfall	13	100	0	.	0	.	0	.	0	.	76	85	89	62	0	.	318	55	25	77	57	59	363	44	327	53	366	36	1633	20
	various	110	56	0	.	0	.	0	.	0	.	111	55	22	75	140	80	167	36	31	64	69	70	214	33	192	42	408	26	1465	15
	indeterminable	164	40	0	.	61	61	0	.	0	.	789	33	1215	22	164	42	1066	20	342	43	320	46	1537	20	2570	16	1203	22	9432	8
	wood harvest	8	100	0	.	0	.	0	.	0	.	15	72	42	100	7	100	48	55	37	100	0	.	37	56	131	42	18	100	342	26
	other human activity	0	.	0	.	0	.	0	.	0	.	143	64	45	63	15	100	55	56	71	100	0	.	118	58	150	37	42	71	640	24
	weather	19	100	0	.	0	.	0	.	0	.	43	48	125	42	12	100	166	38	134	63	25	76	260	32	225	34	336	27	1344	14
	lying living trees	0	.	0	.	0	.	0	.	0	.	37	72	0	.	0	.	18	100	0	.	35	71	181	65	53	58	18	100	341	38
	dead trees	44	61	0	.	134	84	0	.	0	.	895	35	901	30	599	56	1278	25	244	46	204	53	1445	22	2198	25	1091	23	9033	10
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
1201-1400 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	5032	16	0	.	207	78	0	.	0	.	3484	21	3462	22	2796	20	3028	25	1457	34	1126	35	5075	20	3397	22	4695	20	33759	7
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	33	100	33	100
	rockfall	21	100	0	.	0	.	0	.	0	.	337	60	282	47	178	45	199	48	158	71	346	56	459	40	265	54	530	31	2774	16
	various	297	31	0	.	0	.	0	.	0	.	153	50	52	58	234	43	126	42	33	64	154	53	317	50	104	51	445	29	1915	15
	indeterminable	886	19	0	.	59	72	0	.	0	.	687	25	1127	23	749	23	824	24	351	38	452	34	713	24	1466	24	1352	20	8667	8
	wood harvest	111	44	0	.	0	.	0	.	0	.	37	60	43	62	74	83	77	74	0	.	118	55	0	.	109	45	60	50	629	21
	other human activity	83	41	0	.	0	.	0	.	0	.	204	60	19	100	136	49	23	75	0	.	0	.	0	.	127	55	26	76	617	26
	weather	253	45	0	.	7	100	0	.	0	.	150	42	119	37	36	83	98	56	26	100	107	48	101	51	164	53	305	30	1365	15
	lying living trees	0	.	0	.	0	.	0	.	0	.	0	.	36	71	6	100	0	.	35	100	90	60	60	53	0	.	108	43	334	27
	dead trees	813	26	0	.	15	71	0	.	0	.	1088	27	1120	32	931	23	650	29	304	46	829	42	1066	23	1161	24	1116	25	9092	9
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
1001-1200 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	12295	10	0	.	575	58	198	74	140	67	2895	25	6595	15	3456	20	2334	27	1951	30	1640	37	3215	21	2226	29	5567	19	43088	6
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	6	100	72	91	78	84
	rockfall	352	39	0	.	46	100	0	.	0	.	90	78	724	37	102	71	396	53	423	56	246	46	314	54	425	46	819	28	3937	15
	various	422	29	0	.	7	100	0	.	20	74	117	68	158	32	193	34	79	45	438	44	50	49	146	39	205	57	368	45	2203	15
	indeterminable	1664	13	0	.	76	92	7	100	7	100	429	28	928	22	964	23	404	26	427	32	458	36	744	28	786	33	1372	21	8265	8
	wood harvest	742	20	0	.	0	.	0	.	23	100	70	73	309	33	204	43	7	100	22	100	135	54	7	100	26	100	7	100	1553	14
	other human activity	184	38	0	.	0	.	0	.	7	100	26	100	89	66	160	60	0	.	15	100	96	67	7	100	35	71	25	100	645	24
	weather	167	39	0	.	0	.	0	.	33	100	72	45	318	35	77	43	111	46	15	100	18	74	117	39	145	72	312	29	1386	15
	lying living trees	0	.	0	.	0	.	0	.	0	.	15	100	37	100	61	76	18	100	0	.	0	.	122	74	18	100	43	71	314	37
	dead trees	1487	18	0	.	59	75	34	100	0	.	638	30	1326	20	1152	32	466	42	537	36	394	43	954	26	563	32	1114	27	8725	9
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
801-1000 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	11227	11	1258	32	1671	30	2445	30	1317	43	1797	32	8460	15	6638	16	1958	26	963	44	886	32	2645	27	1959	28	5562	26	48786	6
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	rockfall	1017	35	38	100	0	.	0	.	52	100	0	.	293	68	7	100	134	58	397	63	554	35	362	64	88	60	454	32	3395	17
	various	303	30	0	.	34	65	81	47	17	100	117	56	457	22	335	30	17	71	33	71	62	41	84	53	116	44	460	43	2115	13
	indeterminable	2106	16	190	43	275	39	301	31	219	42	318	35	1055	21	1002	22	367	37	213	49	276	38	755	28	775	30	1829	24	9680	8
	wood harvest	591	30	35	66	97	77	171	37	31	81	41	54	482	33	296	32	0	.	22	100	71	55	33	100	59	52	0	0	1928	15
	other human activity	252	38	0	.	0	.	8	100	17	100	39	81	235	53	177	42	26	76	18	100	19	100	0	.	50	74	69	48	910	21
	weather	328	30	48	63	26	78	0	.	37	61	0	0	205	41	178	35	42	62	18	100	47	65	40	71	227	45	530	56	1727	20
	lying living trees	0	.	0	.	0	.	0	.	0	.	0	.	94	55	0	.	8	100	0	.	22	77	18	100	18	100	188	63	348	38
	dead trees	1647	16	226	53	115	42	212	43	50	74	281	41	1302	22	1136	26	555	34	326	47	408	33	726	31	452	28	1746	26	9183	9
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
601-800 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	10625	13	2142	23	5283	21	9388	14	7951	13	923	46	5778	17	3857	22	1459	29	520	60	884	45	1137	48	2132	25	4497	20	56576	5
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	424	69	424	69
	rockfall	328	40	323	60	0	.	24	78	0	.	60	100	336	70	57	71	218	52	128	71	151	76	147	62	147	71	369	31	2287	18
	various	265	33	45	54	497	36	157	39	449	29	68	100	614	47	456	35	92	59	18	100	0	0	76	81	171	31	1238	40	4147	16
	indeterminable	1586	17	380	30	533	32	1321	21	1216	19	122	59	1023	21	1032	23	294	35	165	72	142	59	300	46	570	31	2052	20	10734	7
	wood harvest	507	24	125	46	280	39	706	22	563	24	0	.	402	32	75	51	32	100	6	100	17	73	0	.	33	100	90	100	2836	11
	other human activity	107	49	0	.	125	59	168	58	95	42	0	.	69	50	26	75	15	100	0	.	0	.	0	.	14	71	28	77	648	23
	weather	216	26	34	70	49	43	85	54	308	30	0	.	84	52	78	56	46	58	18	100	15	100	25	76	38	83	774	43	1769	20
	lying living trees	0	.	35	100	0	.	0	.	50	58	0	.	36	71	60	57	0	.	0	.	15	100	36	71	0	.	98	44	330	25
	dead trees	2169	16	425	36	544	26	797	24	859	23	153	77	829	29	882	27	357	35	0	.	299	41	401	40	413	35	2317	21	10446	8
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
=600 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	5135	16	8058	14	3897	19	11462	11	17200	8	0	.	699	56	994	38	648	62	763	56	102	74	1243	37	35	100	6220	18	56456	5
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	126	100	126	100
	rockfall	191	100	108	87	0	.	0	.	0	.	0	.	0	.	373	82	7	100	22	100	18	100	30	100	0	.	426	37	1175	35
	various	310	44	342	29	267	33	202	30	695	21	0	.	0	.	79	100	74	72	44	62	0	.	58	65	0	.	776	36	2846	14
	indeterminable	990	19	1356	16	553	25	963	17	2974	11	0	.	79	71	341	44	153	84	57	57	34	73	131	48	0	.	2801	19	10432	7
	wood harvest	264	30	342	31	128	39	980	21	1146	18	0	.	52	100	51	65	18	100	7	100	0	.	18	100	0	.	0	.	3008	11
	other human activity	54	58	142	37	96	49	89	40	253	64	0	.	0	.	36	65	0	0	0	.	0	.	0	.	0	.	192	41	862	23
	weather	204	35	232	30	150	48	84	39	425	23	0	.	0	.	70	68	44	72	18	100	0	.	36	71	0	.	412	29	1677	12
	lying living trees	62	53	90	44	0	.	0	.	97	41	0	.	0	.	21	74	15	100	0	.	0	.	18	100	0	.	323	41	627	24
	dead trees	1277	24	1356	19	789	29	658	19	1784	15	0	.	64	52	298	42	148	56	82	63	68	80	396	45	0	.	3172	18	10092	8
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
total	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	44884	4	11458	11	12019	12	23493	8	26609	6	12059	12	30860	7	19526	9	15642	10	7472	16	6486	16	29637	7	32994	7	38310	6	311449	2
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	6	100	662	50	669	49
	rockfall	1922	23	469	46	46	100	24	78	52	100	594	39	1887	23	717	45	1390	23	1152	32	1372	23	2106	19	1601	21	3282	12	16614	7
	various	1709	14	387	27	805	25	440	21	1181	17	583	27	1455	22	1436	18	769	24	732	32	359	29	1226	17	1495	14	4099	15	16675	6
	indeterminable	7398	7	1926	13	1556	17	2591	13	4416	9	2658	15	6061	9	4252	10	4089	11	1819	18	1756	17	8001	9	11693	8	12042	7	70258	2
	wood harvest	2224	12	502	24	505	28	1857	14	1764	14	163	37	1330	18	706	21	238	39	94	52	340	31	183	34	419	22	202	50	10526	5
	other human activity	680	20	142	37	220	40	265	39	371	45	421	38	471	31	551	26	153	31	104	72	115	58	527	30	547	22	455	23	5022	9
	weather	1187	15	314	25	232	34	169	33	803	17	265	28	880	18	450	22	598	20	229	41	236	29	1266	18	1189	18	3014	16	10836	6
	lying living trees	62	53	125	42	0	.	0	.	147	34	52	59	281	36	170	37	58	52	35	100	162	39	589	29	436	39	779	24	2895	12
	dead trees	7437	8	2007	16	1656	18	1702	14	2693	12	3234	15	6379	11	5125	13	4605	13	1587	20	2299	19	8577	10	8222	10	11627	8	67148	3
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.

Table citation

Abegg, M.; Ahles, P.; Allgaier Leuch, B.; Cioldi, F.; Didion, M.; Düggelin, C.; Fischer, C.; Herold, A.; Meile, R.; Rohner, B.; Rösler, E.; Speich, S.; Temperli, C.; Traub, B.,
2023: Swiss national forest inventory - Result table No. 1346957. Birmensdorf, Swiss Federal Research Institute WSL

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