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: n/ha
evaluation area: accessible forest without shrub forest NFI4/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)	n/ha	±%	n/ha	±%	n/ha	±%	n/ha	±%	n/ha	±%	n/ha	±%	n/ha	±%	n/ha	±%	n/ha	±%	n/ha	±%	n/ha	±%	n/ha	±%	n/ha	±%	n/ha	±%	n/ha	±%
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	.	1387	0	200	0	0	.	242	37	700	0	98	72	204	12	266	9	220	11	243	6
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	99	0	100
	rockfall	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	12	24	4	42	19	51	9	25
	various	0	.	0	.	0	.	0	.	0	.	0	.	50	0	0	.	10	53	0	.	39	72	9	35	15	24	12	22	13	16
	indeterminable	0	.	0	.	0	.	0	.	0	.	42	0	190	0	0	.	106	28	150	0	84	72	75	15	105	10	83	13	92	7
	wood harvest	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	3	52	0	75	0	.	1	45
	other human activity	0	.	0	.	0	.	0	.	0	.	0	.	40	0	0	.	3	95	0	.	0	.	11	45	1	46	4	67	5	34
	weather	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	25	72	15	24	7	25	34	36	15	20
	lying living trees	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	5	61	11	37	5	47	7	29
	dead trees	0	.	0	.	0	.	0	.	0	.	0	.	640	0	0	.	75	41	50	0	0	.	69	18	69	14	49	25	66	10
	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	.	320	38	450	29	620	0	239	13	104	29	337	41	283	13	271	9	254	12	280	6
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	rockfall	0	.	0	.	0	.	0	.	0	.	13	62	25	49	0	.	12	60	0	.	0	.	7	34	10	35	11	50	10	20
	various	0	.	0	.	0	.	0	.	0	.	7	57	22	37	0	.	23	60	61	75	8	70	8	28	14	27	18	31	16	17
	indeterminable	0	.	0	.	0	.	0	.	0	.	131	52	100	27	0	.	96	19	115	32	37	35	101	13	93	10	60	17	89	7
	wood harvest	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	6	98	0	.	0	.	0	99	1	45	1	99	1	49
	other human activity	0	.	0	.	0	.	0	.	0	.	3	93	6	97	0	.	4	58	0	.	2	94	10	50	7	39	2	60	6	26
	weather	0	.	0	.	0	.	0	.	0	.	0	.	10	58	0	.	15	39	0	.	8	69	19	40	10	31	14	21	13	18
	lying living trees	0	.	0	.	0	.	0	.	0	.	0	.	12	89	50	0	4	98	0	.	0	.	3	46	1	99	1	99	2	39
	dead trees	0	.	0	.	0	.	0	.	0	.	75	47	97	44	290	0	106	30	37	44	30	42	95	22	45	15	32	22	65	11
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
1401-1600 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	154	19	0	.	225	29	0	.	0	.	278	28	261	15	273	23	264	13	314	23	186	21	285	12	295	10	357	11	285	5
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	rockfall	3	96	0	.	0	.	0	.	0	.	10	75	16	60	0	.	32	50	5	73	12	53	19	39	16	43	19	32	17	19
	various	31	38	0	.	0	.	0	.	0	.	12	52	2	74	25	71	10	33	6	59	14	64	11	28	6	41	24	20	12	13
	indeterminable	42	23	0	.	35	43	0	.	0	.	97	24	101	14	33	31	78	12	97	25	73	32	82	13	85	11	73	14	80	5
	wood harvest	2	96	0	.	0	.	0	.	0	.	2	69	3	99	1	97	3	53	7	96	0	.	2	55	4	41	1	99	3	25
	other human activity	0	.	0	.	0	.	0	.	0	.	16	61	8	60	3	98	6	51	13	97	0	.	8	45	6	36	2	70	6	21
	weather	6	73	0	.	0	.	0	.	0	.	5	44	10	39	2	98	10	36	25	58	5	72	15	29	9	28	19	22	11	13
	lying living trees	0	.	0	.	0	.	0	.	0	.	4	69	0	.	0	.	1	99	11	96	21	66	10	58	3	52	4	58	4	28
	dead trees	12	46	0	.	78	72	0	.	0	.	105	26	72	26	102	49	83	19	54	32	72	42	74	17	73	21	69	17	75	8
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
1201-1400 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	275	12	0	.	225	36	0	.	0	.	337	13	260	15	232	12	289	17	287	18	234	18	377	12	266	14	255	14	281	5
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	2	99	0	100
	rockfall	1	99	0	.	0	.	0	.	0	.	29	57	22	42	13	43	24	39	60	63	90	38	30	37	20	51	35	24	26	15
	various	15	27	0	.	0	.	0	.	0	.	19	38	10	66	24	35	12	38	18	57	33	37	49	44	8	44	22	26	21	15
	indeterminable	44	15	0	.	53	44	0	.	0	.	75	19	90	15	58	16	78	16	67	22	84	21	61	17	114	16	73	14	72	5
	wood harvest	5	42	0	.	0	.	0	.	0	.	3	58	3	61	5	82	7	72	0	.	20	49	0	.	8	43	3	49	5	21
	other human activity	4	39	0	.	0	.	0	.	0	.	22	49	1	99	10	47	2	74	1	98	0	.	1	99	12	46	1	75	5	24
	weather	12	43	0	.	6	85	0	.	0	.	13	39	9	34	3	81	9	53	19	67	18	41	7	48	14	44	17	25	11	14
	lying living trees	0	.	0	.	0	.	0	.	0	.	0	.	3	69	0	99	0	.	23	78	15	55	5	44	0	.	5	41	4	32
	dead trees	40	23	0	.	13	43	0	.	0	.	96	21	82	27	68	17	62	22	69	37	150	31	87	16	92	18	56	21	73	7
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
1001-1200 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	315	6	0	.	411	27	293	23	139	35	348	16	324	10	246	12	298	16	333	17	266	28	313	10	241	18	290	12	300	4
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	1	99	3	90	0	84
	rockfall	9	38	0	.	33	88	0	.	0	.	9	77	33	35	6	70	48	48	76	45	40	40	25	49	37	41	37	25	26	14
	various	11	28	0	.	5	88	0	.	20	48	12	66	7	30	17	33	15	41	70	37	8	44	17	33	23	45	20	38	16	13
	indeterminable	43	10	0	.	54	77	10	69	7	82	73	28	49	17	66	15	55	17	74	20	82	24	69	20	106	23	75	15	62	6
	wood harvest	19	18	0	.	0	.	0	.	23	82	10	56	14	31	17	35	1	98	4	97	22	49	1	99	3	80	0	99	11	13
	other human activity	5	37	0	.	0	.	0	.	7	82	11	77	5	57	10	58	0	.	8	72	17	58	1	69	5	55	1	99	5	22
	weather	4	38	0	.	0	.	0	.	33	82	18	50	14	33	7	42	13	41	11	57	6	57	11	31	14	61	17	23	11	13
	lying living trees	0	.	0	.	0	.	0	.	0	.	2	99	2	99	4	75	2	98	11	97	0	.	11	64	2	99	6	70	3	33
	dead trees	38	17	0	.	42	55	51	69	0	.	70	22	60	17	76	27	66	31	86	28	64	36	85	20	56	22	56	22	59	7
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
801-1000 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	324	7	319	14	292	18	418	18	444	22	279	22	344	10	346	9	336	11	328	25	137	22	365	15	210	20	402	18	329	4
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	rockfall	29	34	8	96	0	.	0	.	14	95	0	.	11	67	0	99	21	53	116	51	107	23	47	60	9	57	33	27	23	16
	various	9	29	0	.	6	59	14	40	17	56	17	50	18	19	19	25	15	80	17	54	9	36	11	49	12	40	29	40	15	12
	indeterminable	60	13	44	30	48	31	51	20	80	20	55	25	41	18	59	17	69	26	63	33	54	27	100	19	85	22	122	18	66	6
	wood harvest	17	28	15	51	17	73	29	28	8	76	6	49	19	31	19	32	0	.	6	96	11	52	4	98	9	44	0	.	13	14
	other human activity	7	37	4	96	0	.	1	97	22	77	6	78	9	52	9	38	4	73	5	95	3	97	1	98	5	72	4	45	6	19
	weather	9	29	11	57	5	74	0	.	10	54	0	.	8	40	9	31	15	58	7	72	15	44	5	68	24	40	35	52	12	19
	lying living trees	0	.	0	.	0	.	0	.	0	.	0	.	4	54	0	.	1	97	5	95	3	74	2	98	2	98	13	56	2	35
	dead trees	47	13	50	45	20	35	36	35	17	54	42	32	58	20	61	22	90	23	105	29	80	22	97	22	48	21	119	20	63	7
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
601-800 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	333	8	236	13	324	15	324	9	258	8	409	20	326	9	300	15	316	13	316	40	245	34	262	37	263	15	285	14	301	4
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	27	68	2	69
	rockfall	10	39	36	56	0	.	1	77	0	.	26	90	19	69	4	69	47	46	78	54	42	69	32	56	18	68	25	26	12	18
	various	10	30	5	50	30	33	5	38	14	28	30	92	34	45	35	31	20	54	11	88	0	.	17	76	21	23	78	38	22	15
	indeterminable	50	14	42	24	33	29	46	19	39	16	54	44	57	16	80	17	64	23	100	56	39	52	66	37	70	24	129	15	57	6
	wood harvest	16	22	14	42	17	36	24	20	18	22	0	.	22	29	6	48	7	97	4	91	5	68	0	.	4	98	6	99	15	10
	other human activity	3	49	3	98	8	58	6	57	3	41	0	.	4	48	2	73	3	97	0	.	0	.	0	.	2	68	2	75	4	22
	weather	7	25	7	56	3	40	3	53	10	28	0	.	5	51	6	54	10	52	11	88	4	96	9	54	5	81	49	40	10	20
	lying living trees	0	.	4	98	0	.	0	.	2	57	0	.	2	69	5	54	0	.	0	.	4	96	8	65	0	.	6	42	2	24
	dead trees	68	13	47	30	33	22	27	21	28	21	68	66	46	25	69	22	77	23	0	.	83	30	104	25	51	29	146	17	56	7
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
=600 m	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	244	10	278	9	267	12	283	7	242	5	0	.	383	34	215	26	463	36	427	27	165	24	256	25	100	0	308	13	267	3
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	6	99	1	100
	rockfall	9	99	4	87	0	.	0	.	0	.	0	.	0	.	81	77	5	85	10	93	30	71	10	68	0	.	23	32	6	32
	various	15	40	12	28	20	28	5	29	10	21	0	.	0	.	17	96	53	53	21	48	0	.	22	53	0	.	39	32	14	13
	indeterminable	47	15	47	12	38	19	24	14	42	9	0	.	43	57	74	34	109	66	49	36	55	19	40	39	0	.	142	13	50	6
	wood harvest	13	26	12	30	8	36	24	19	16	17	0	.	29	91	11	59	13	85	4	91	0	.	4	97	0	.	0	.	14	10
	other human activity	3	56	5	36	6	47	3	40	4	64	0	.	0	.	8	60	0	.	8	91	0	.	15	96	0	.	9	39	5	22
	weather	10	33	8	28	10	46	2	38	6	22	0	.	0	.	15	62	32	50	9	91	0	.	7	66	0	.	20	25	8	12
	lying living trees	3	51	3	43	0	.	0	.	1	41	0	.	0	.	5	69	11	90	0	.	0	.	4	97	0	.	15	39	3	24
	dead trees	60	20	47	16	56	23	18	18	25	14	0	.	35	28	64	31	105	24	61	36	110	39	86	33	0	.	157	13	49	7
	total	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.	.
total	n/a	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.
	no visible damage	301	4	273	7	295	8	309	6	253	4	329	9	322	5	283	6	284	6	308	9	220	12	284	5	267	4	296	5	288	2
	fire	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	.	0	100	4	50	1	49
	rockfall	13	23	11	46	1	100	0	77	0	100	14	38	20	22	10	45	27	23	52	29	54	19	19	17	13	19	25	11	16	7
	various	12	13	9	26	20	23	6	20	11	16	15	24	15	20	23	16	15	21	30	27	13	24	16	20	13	13	29	14	16	5
	indeterminable	49	6	45	10	38	14	34	11	42	7	77	12	64	7	62	8	78	7	79	11	65	12	79	6	96	5	93	6	67	2
	wood harvest	15	12	13	22	12	27	24	13	16	13	5	34	13	17	12	20	4	38	3	51	11	29	2	33	3	21	1	50	9	5
	other human activity	4	20	4	32	5	39	4	36	4	41	13	32	6	27	8	25	3	30	6	51	4	51	7	26	5	19	3	22	5	8
	weather	8	15	8	23	6	33	2	33	7	17	9	30	9	17	7	21	12	18	14	33	10	23	13	16	10	15	25	14	11	6
	lying living trees	0	52	3	41	0	.	0	.	1	33	1	58	3	36	2	37	2	49	11	51	7	39	6	26	4	30	7	21	3	11
	dead trees	49	7	47	14	41	15	23	13	25	12	79	12	66	10	72	11	81	10	67	15	83	15	83	8	63	8	84	7	62	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. 1345760. Birmensdorf, Swiss Federal Research Institute WSL

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