OR/15/021 Technical information - Revision history

Dbk at 11:13, 28 July 2015

2015-07-28T11:13:31Z

← Older revision		Revision as of 12:13, 28 July 2015
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	\|-		\|-
	\| CLASS5		\| CLASS5
	\| The Total_of column is classified into 5 classes using natural breaks (Jenk’s Classification), values of ~~1-5~~		\| The Total_of column is classified into 5 classes using natural breaks (Jenk’s Classification), values of 1–5
	\|-		\|-
	\| CLASS10		\| CLASS10
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	===GeoSure Hazard ‘Visualisation’ layers===		===GeoSure Hazard ‘Visualisation’ layers===
	The six HV layers are directly derived from the master GeoSure hazard layers as follows:		The six HV layers are directly derived from the master GeoSure hazard layers as follows:
	* Each of the six master GeoSure hazard layers is already classed into 5 classes ~~A-E~~ (see Table 3). Classes D and E are selected from each of the master layers to create six new Hazard Visualisation (HV) layers.		* Each of the six master GeoSure hazard layers is already classed into 5 classes A–E (see Table 3). Classes D and E are selected from each of the master layers to create six new Hazard Visualisation (HV) layers.
	* The polygons in each of the new HV layers are dissolved to remove boundaries between classes D and E to improve performance and reduce complexity.		* The polygons in each of the new HV layers are dissolved to remove boundaries between classes D and E to improve performance and reduce complexity.

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	\|}		\|}

	Before use in the DPD, these unified rating values in the table are then multiplied by 10 to allow the use of integer values. For example a class ~~“D”~~ shrink swell pixel will have a value of 10 x 10 = 100. This is to enable geo-processing operations to compute weighted averages for each postcode area.		Before use in the DPD, these unified rating values in the table are then multiplied by 10 to allow the use of integer values. For example a class 'D' shrink swell pixel will have a value of 10 x 10 = 100. This is to enable geo-processing operations to compute weighted averages for each postcode area.


	Therefore the ranges of the data in the DPD are as follows:		Therefore the ranges of the data in the DPD are as follows:
	: Collapsible Deposits Occurrence Factor: ~~0-5~~ Compressible		: Collapsible Deposits Occurrence Factor: 0–5 Compressible
	: Ground Occurrence Factor: ~~0-100~~		: Ground Occurrence Factor: 0–100
	: Soluble Rocks Occurrence Factor: ~~0-10~~		: Soluble Rocks Occurrence Factor: 0–10
	: Running Sand Occurrence Factor: ~~0-5~~		: Running Sand Occurrence Factor: 0–5
	: Shrink-Swell Occurrence Factor: ~~0-200~~		: Shrink-Swell Occurrence Factor: 0–200
	: Landslides Occurrence Factor: ~~0-20~~		: Landslides Occurrence Factor: 0–20

	Although there is a theoretical maximum TOF of 5+100+10+5+200+20 = 340, the maximum score achieved under existing geological conditions is 213.		Although there is a theoretical maximum TOF of 5+100+10+5+200+20 = 340, the maximum score achieved under existing geological conditions is 213.
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	* In order to assign a score to each postcode unit, statistics are calculated using the buffered postcode layer in conjunction with each of the six TOF hazard feature layers. This process considers each hazard in turn and calculates the average values proportional to their spatial coverage, that occur within each of the 300m circular buffered postcode areas. These average values for each hazard are then added to the output Derived Postcode Database as ‘occurrence factors’.		* In order to assign a score to each postcode unit, statistics are calculated using the buffered postcode layer in conjunction with each of the six TOF hazard feature layers. This process considers each hazard in turn and calculates the average values proportional to their spatial coverage, that occur within each of the 300m circular buffered postcode areas. These average values for each hazard are then added to the output Derived Postcode Database as ‘occurrence factors’.

	Figure 1 and Figure 2 show the distribution of the data within the DPD, as represented by the numbers of postcodes plotted against the Total Occurrence Factor (TOF). The total range of the TOF is ~~0-213~~. The distribution is quite stepped. This is because the GeoSure hazard rating is broken down into the five classes (A-E). Although the change in hazard between each class is incremental (E is one step worse than D is one step worse than C and so on) the likely occurrence of each level of hazard may vary by an order of magnitude between classes. Figure 1 and Figure 2] also show how natural breaks have been selected using the Jenks’ Classification method in the distribution in order to derive the fivefold (Class 5) and tenfold (Class 10) classifications displayed in the DPD (last two columns of Figure 1]).		Figure 1 and Figure 2 show the distribution of the data within the DPD, as represented by the numbers of postcodes plotted against the Total Occurrence Factor (TOF). The total range of the TOF is 0–213. The distribution is quite stepped. This is because the GeoSure hazard rating is broken down into the five classes (A-E). Although the change in hazard between each class is incremental (E is one step worse than D is one step worse than C and so on) the likely occurrence of each level of hazard may vary by an order of magnitude between classes. Figure 1 and Figure 2] also show how natural breaks have been selected using the Jenks’ Classification method in the distribution in order to derive the fivefold (Class 5) and tenfold (Class 10) classifications displayed in the DPD (last two columns of Figure 1]).

	These classifications are provided in order to aid interpretation of the hazard scale and also to allow easier representation of the data in mapping tools (e.g. by colouring up the postcode points in a GIS if so wished).		These classifications are provided in order to aid interpretation of the hazard scale and also to allow easier representation of the data in mapping tools (e.g. by colouring up the postcode points in a GIS if so wished).

	In detail, the Total Occurrence Factor (TOF) class breaks in the DPD in version 7 of the GeoSure Insurance Product are as follows (against the overall ~~0-213~~ scale of the TOF):		In detail, the Total Occurrence Factor (TOF) class breaks in the DPD in version 7 of the GeoSure Insurance Product are as follows (against the overall 0–213 scale of the TOF):
	: Class 5 breaks are: 0,14,27,52,115,213		: Class 5 breaks are: 0,14,27,52,115,213
	: Class 10 breaks are: 0,7,17,24,29,36,52,107,116,133,213		: Class 10 breaks are: 0,7,17,24,29,36,52,107,116,133,213
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	==== TOF values of 40-94 ====		==== TOF values of 40-94 ====
	TOF values within the range ~~40-94~~ range (upper Class 3 and lower Class 4 of the fivefold Class 5 division) are relatively rare in the dataset (Figure 1) because of the way the data has been calculated. If values in this range are encountered they may result from the contribution of a single hazard or the combined effects of two or more hazards.		TOF values within the range 40–94 range (upper Class 3 and lower Class 4 of the fivefold Class 5 division) are relatively rare in the dataset (Figure 1) because of the way the data has been calculated. If values in this range are encountered they may result from the contribution of a single hazard or the combined effects of two or more hazards.

	In general terms, TOF values towards the top end of this ~~40-95~~ range (i.e. into Class 4) indicate that one or more hazards may be present that are a ''significant ''hazard to a low-rise building and of ''significant ''insurance risk. Again, in general terms only, TOF values towards the lower end of the range (i.e. into Class 3) indicate that one or more hazards may be present, but that they are only likely to be of ''possible ''hazard to a low-rise building and of ''possible ''insurance risk, particularly if modifications are made to the ground, for example, changes to groundwater by tree removal, or building work.		In general terms, TOF values towards the top end of this 40–95 range (i.e. into Class 4) indicate that one or more hazards may be present that are a ''significant ''hazard to a low-rise building and of ''significant ''insurance risk. Again, in general terms only, TOF values towards the lower end of the range (i.e. into Class 3) indicate that one or more hazards may be present, but that they are only likely to be of ''possible ''hazard to a low-rise building and of ''possible ''insurance risk, particularly if modifications are made to the ground, for example, changes to groundwater by tree removal, or building work.

	Reference to the individual Occurrence Factors in the DPD (and comparing the values to their ranges as quoted above) and/or to the HV layers in the GIS should indicate to users which of the hazards are present.		Reference to the individual Occurrence Factors in the DPD (and comparing the values to their ranges as quoted above) and/or to the HV layers in the GIS should indicate to users which of the hazards are present.

	==== TOF values of 10 to 39 ====		==== TOF values of 10 to 39 ====
	TOF values in the ~~10-39~~ range (higher Class1, Class 2, and lower Class 3 on the fivefold Class 5 scale), which are common in the dataset, indicate some form of natural ground stability hazard being present at a level which may cause ground movement.		TOF values in the 10–39 range (higher Class1, Class 2, and lower Class 3 on the fivefold Class 5 scale), which are common in the dataset, indicate some form of natural ground stability hazard being present at a level which may cause ground movement.

	The combination of anticipated severity of any hazard event and frequency of the hazard event means, however, that it is only likely to be of ''possible ''concern for property insurance. However, in such areas, caution should still be exercised as local variations in the geology, or local effects (for example, changes to groundwater by tree removal) or modifications to the ground, could exacerbate the effects of these hazards such that they may become of concern to property stability.		The combination of anticipated severity of any hazard event and frequency of the hazard event means, however, that it is only likely to be of ''possible ''concern for property insurance. However, in such areas, caution should still be exercised as local variations in the geology, or local effects (for example, changes to groundwater by tree removal) or modifications to the ground, could exacerbate the effects of these hazards such that they may become of concern to property stability.
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	Reference to the individual Occurrence Factors in the DPD (and comparing the values to their ranges as quoted above) should indicate to users which of the hazards are present.		Reference to the individual Occurrence Factors in the DPD (and comparing the values to their ranges as quoted above) should indicate to users which of the hazards are present.

	==== TOF values of ~~1-9~~ ====		==== TOF values of 1–9 ====
	TOF values in the ~~1-9~~ range (lower Class 1 on the Class 5 scale), which are common in the dataset, indicate the presence of one or more ground movement hazards, but at a level which is likely to be ''insignificant ''in terms of property insurance.		TOF values in the 1–9 range (lower Class 1 on the Class 5 scale), which are common in the dataset, indicate the presence of one or more ground movement hazards, but at a level which is likely to be ''insignificant ''in terms of property insurance.

	==== TOF values of 0 ====		==== TOF values of 0 ====

Dbk: /* GeoSure Derived Postcode Database */

2015-05-19T15:57:45Z

GeoSure Derived Postcode Database

← Older revision		Revision as of 16:57, 19 May 2015
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	{\| class="wikitable"		{\| class="wikitable"
	\|+ Table 4 Calibration of the hazard Occurrence Rating.		\|+ Table 4 Calibration of the hazard Occurrence Rating.
	\| '''Estimated~~'''''' ''''''~~Frequency of Occurrence'''		\| '''Estimated Frequency of Occurrence'''
	\| '''Numerical Representation of Estimated Frequency of Occurrence'''		\| '''Numerical Representation of Estimated Frequency of Occurrence'''
	\| '''Occurrence~~'''''' ''''''~~Rating'''		\| '''Occurrence Rating'''
	\|-		\|-
	\| once in 1 years		\| once in 1 years

Dbk: /* GeoSure Derived Postcode Database */

2015-05-19T15:57:27Z

GeoSure Derived Postcode Database

← Older revision		Revision as of 16:57, 19 May 2015
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	\|}		\|}

	{\| ~~border~~="~~0" cellspacing="0" cellpadding="0~~"		{\| class="wikitable"
	\|+ Table 4 Calibration of the hazard Occurrence Rating.		\|+ Table 4 Calibration of the hazard Occurrence Rating.

	\| '''Estimated'''''' ''''''Frequency of Occurrence'''		\| '''Estimated'''''' ''''''Frequency of Occurrence'''
	\| '''Numerical Representation of Estimated Frequency of Occurrence'''		\| '''Numerical Representation of Estimated Frequency of Occurrence'''

Dbk at 15:56, 19 May 2015

2015-05-19T15:56:32Z

← Older revision		Revision as of 16:56, 19 May 2015
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	: Class 10 breaks are: 0,7,17,24,29,36,52,107,116,133,213		: Class 10 breaks are: 0,7,17,24,29,36,52,107,116,133,213

	[[Image:~~OR15021fig1~~.jpg\|thumb\|center\|400px\| '''Figure 1''' Distribution of postcodes in the DPD against the TOF (0-213) range; also showing position of the Class 5 natural breaks.]]		[[Image:OR15021 fig1.jpg\|thumb\|center\|400px\| '''Figure 1''' Distribution of postcodes in the DPD against the TOF (0-213) range; also showing position of the Class 5 natural breaks.]]

	[[Image:~~OR15021fig2~~.jpg\|thumb\|center\|400px\| '''Figure 2''' Distribution of postcodes in the DPD against the TOF (0-213) range; also showing position of the Class 10 natural breaks.]]		[[Image:OR15021 fig2.jpg\|thumb\|center\|400px\| '''Figure 2''' Distribution of postcodes in the DPD against the TOF (0-213) range; also showing position of the Class 10 natural breaks.]]

	==Interpreting the total occurrence factor scale in the derived postcode database==		==Interpreting the total occurrence factor scale in the derived postcode database==
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	Data is provided for Great Britain. The Isle of Man is not covered.		Data is provided for Great Britain. The Isle of Man is not covered.

	[[Image:~~OR15021fig3~~.jpg\|thumb\|center\|400px\| '''Figure 3''' The coverage of the GeoSure Insurance Product (GIP) dataset.]]		[[Image:OR15021 fig3.jpg\|thumb\|center\|400px\| '''Figure 3''' The coverage of the GeoSure Insurance Product (GIP) dataset.]]

	==Data format==		==Data format==

Dbk: /* TOF values of 40-94 */

2015-05-19T14:12:05Z

TOF values of 40-94

← Older revision		Revision as of 15:12, 19 May 2015
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	==== TOF values of 40-94 ====		==== TOF values of 40-94 ====
	TOF values within the range 40-94 range (upper Class 3 and lower Class 4 of the fivefold Class 5 division) are relatively rare in the dataset (~~[file:///W:/PP/GraphicCommunications/Graphic%20Design/Live_Jobs/2014%20Reports/2015/15021/OR15021.docx#_bookmark2~~ Figure 1]) because of the way the data has been calculated. If values in this range are encountered they may result from the contribution of a single hazard or the combined effects of two or more hazards.		TOF values within the range 40-94 range (upper Class 3 and lower Class 4 of the fivefold Class 5 division) are relatively rare in the dataset (Figure 1) because of the way the data has been calculated. If values in this range are encountered they may result from the contribution of a single hazard or the combined effects of two or more hazards.

	In general terms, TOF values towards the top end of this 40-95 range (i.e. into Class 4) indicate that one or more hazards may be present that are a ''significant ''hazard to a low-rise building and of ''significant ''insurance risk. Again, in general terms only, TOF values towards the lower end of the range (i.e. into Class 3) indicate that one or more hazards may be present, but that they are only likely to be of ''possible ''hazard to a low-rise building and of ''possible ''insurance risk, particularly if modifications are made to the ground, for example, changes to groundwater by tree removal, or building work.		In general terms, TOF values towards the top end of this 40-95 range (i.e. into Class 4) indicate that one or more hazards may be present that are a ''significant ''hazard to a low-rise building and of ''significant ''insurance risk. Again, in general terms only, TOF values towards the lower end of the range (i.e. into Class 3) indicate that one or more hazards may be present, but that they are only likely to be of ''possible ''hazard to a low-rise building and of ''possible ''insurance risk, particularly if modifications are made to the ground, for example, changes to groundwater by tree removal, or building work.

Dbk: Protected "OR/15/021 Technical information" ([Edit=Allow only administrators] (indefinite) [Move=Allow only administrators] (indefinite)) [cascading]

2015-05-19T14:08:00Z

Protected "OR/15/021 Technical information" ([Edit=Allow only administrators] (indefinite) [Move=Allow only administrators] (indefinite)) [cascading]

← Older revision		Revision as of 15:08, 19 May 2015
(No difference)

Dbk: /* Coverage */

2015-05-19T13:58:14Z

Coverage

← Older revision		Revision as of 14:58, 19 May 2015
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	Data is provided for Great Britain. The Isle of Man is not covered.		Data is provided for Great Britain. The Isle of Man is not covered.

	[[Image:OR15021fig3.jpg\|thumb\|center\|400px\| '''Figure 3''' The coverage of the GeoSure Insurance Product (GIP) dataset ==		[[Image:OR15021fig3.jpg\|thumb\|center\|400px\| '''Figure 3''' The coverage of the GeoSure Insurance Product (GIP) dataset.]]

	==Data format==		==Data format==

Dbk: /* GeoSure Derived Postcode Database */

2015-05-19T13:57:44Z

GeoSure Derived Postcode Database

← Older revision		Revision as of 14:57, 19 May 2015
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	[[Image:OR15021fig1.jpg\|thumb\|center\|400px\| '''Figure 1''' Distribution of postcodes in the DPD against the TOF (0-213) range; also showing position of the Class 5 natural breaks.]]		[[Image:OR15021fig1.jpg\|thumb\|center\|400px\| '''Figure 1''' Distribution of postcodes in the DPD against the TOF (0-213) range; also showing position of the Class 5 natural breaks.]]

	[[Image:OR15021fig2.jpg\|thumb\|center\|400px\| '''Figure 2''' Distribution of postcodes in the DPD against the TOF (0-213) range; also showing position of the Class 10 natural breaks.~~'''~~		[[Image:OR15021fig2.jpg\|thumb\|center\|400px\| '''Figure 2''' Distribution of postcodes in the DPD against the TOF (0-213) range; also showing position of the Class 10 natural breaks.]]

	==Interpreting the total occurrence factor scale in the derived postcode database==		==Interpreting the total occurrence factor scale in the derived postcode database==

Dbk: /* GeoSure Derived Postcode Database */

2015-05-19T13:57:12Z

GeoSure Derived Postcode Database

← Older revision		Revision as of 14:57, 19 May 2015
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	{\| class="wikitable"		{\| class="wikitable"
	\|+ Table 3 Normalisation table for GeoSure hazards applied to low rise structures for the insurance industry.		\|+ Table 3 Normalisation table for GeoSure hazards applied to low rise structures for the insurance industry.
			\| colspan="2" \|
	\| ~~rowspan~~="2" \|
	\| colspan="2" \| '''Landslide'''		\| colspan="2" \| '''Landslide'''
	\| colspan="2" \| '''Compressible'''		\| colspan="2" \| '''Compressible'''

Dbk: /* GeoSure Derived Postcode Database */

2015-05-19T13:55:51Z

GeoSure Derived Postcode Database

← Older revision		Revision as of 14:55, 19 May 2015
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	\| <p align="center">0.01</p>		\| <p align="center">0.01</p>
	\| <p align="center">1</p>		\| <p align="center">1</p>
	\| <p align="center">0.002		\| <p align="center">0.002</p>
	\| <p align="center">0.2</p>		\| <p align="center">0.2</p>
	\| <p align="center">0.1</p>		\| <p align="center">0.1</p>

← Older revision		Revision as of 14:57, 19 May 2015
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	{\| class="wikitable"		{\| class="wikitable"
	\|+ Table 3 Normalisation table for GeoSure hazards applied to low rise structures for the insurance industry.		\|+ Table 3 Normalisation table for GeoSure hazards applied to low rise structures for the insurance industry.
			\| colspan="2" \|
	\| ~~rowspan~~="2" \|
	\| colspan="2" \| '''Landslide'''		\| colspan="2" \| '''Landslide'''
	\| colspan="2" \| '''Compressible'''		\| colspan="2" \| '''Compressible'''