Extrapolate Survey Tool

Top 

PTSS Company Logo

 

Extrapolate Survey Tool

 

The Extrapolate Survey tool is a tool in all our spatial products that allows you to broaden a set of survey results already gotten into a wider area based on certain criteria; it can be found here:

EXTRAP~1_img2

 

Before using this tool, you will need to have some things set up.

 

Firstly, you will need a spreadsheet of your survey results:

EXTRAP~1_img3

 

In my survey data there is data about percentage of people who use a particular bank in a particular enumeration area (EA).

 

In order to use this data in the tool it will need to be added as a layer in the spatial pane:

EXTRAP~1_img4

 

 

 

EXTRAP~1_img5

 

EXTRAP~1_img6

 

If you have no coordinate data for the areas in your survey results then it is just added as a data layer, meaning it does not display on the scene but just holds data(which is the case in this example).

 

The next thing you would have is a set of data with the same areas as those in your survey results and more, plus some extra information for those areas that your survey results don’t have such as Dominant Race in that area or Dominant Income. For this I have a Demographics layer which actually exits as a SpatialVU file and I will bring it in: (if this data existed as a spreadsheet you would go through the same steps above to add as it as a layer):

 

 

 

EXTRAP~1_img7

EXTRAP~1_img8

 

EXTRAP~1_img9

 

EXTRAP~1_img10

 

This demographics data does have coordinate data as well, so it is displayed on the scene.

 

Now the next thing you would want to do is a join of these two sets of data to have all this data nicely linked up and in one place. To do this you use the Join Layers tool. (to see how to use this tool refer to the Join Layers Tool manual):

EXTRAP~1_img11

 

After having done the join, your data will now be linked up:

EXTRAP~1_img12

 

EXTRAP~1_img13

 

I will filter out the blanks and see how many areas were surveyed:

EXTRAP~1_img14

 

EXTRAP~1_img15

 

As you can see 1557 areas were surveyed.

 

Now what we would like to do is expand these survey results into more areas so let’s go ahead and open the Extrapolate Survey tool:

EXTRAP~1_img16

 

The first step is to choose which layer is the Survey Layer:

EXTRAP~1_img17

 

Then you need to choose your Area Key in your survey results data which is basically the unique identifier for the areas surveyed:
EXTRAP~1_img18

 

Next, choose which layer is the Extrapolation Layer, which is the layer that the survey results will be extrapolated to:

EXTRAP~1_img19

 

Then you need to choose an Area Key in this set of data as well and it will be a key shared by your survey layer:

EXTRAP~1_img20

 

Next you will choose the Value Columns in your survey layer that you would like to be extrapolated to the extrapolation layer:

EXTRAP~1_img21

 

Below this is an Add Column Values to Extrapolation button which you would press if these columns didn’t also exist in the extrapolation layer, but luckily we did a join so they do exist and the extrapolated data can be populated there:

EXTRAP~1_img22

 

Next you will choose what columns in your extrapolation layer you will use to act as a signature for a particular surveyed area, meaning your surveyed areas will be segmented according to particular characteristics in the Segmentation Columns chosen and then any un-surveyed area(which is what we are trying to extrapolate into) which shares the same signature will have that survey data extrapolated into it, this is the essence of what this tool does:

EXTRAP~1_img23

 

Now what you can do before you extrapolate is have Calculate only ticked on and then click Extrapolate, the calculations done by the tool will be populated in the grid below and you can view them:

EXTRAP~1_img24

So as you can see here it created a total of 19 segments each with a unique signature, and as an example in the first row you can see there are 976 areas that have a signature of Dominant Race Black African and Dominant Income 0.

 

Once you have seen the calculations you can now untick Calculate only and click Extrapolate to do the extrapolation:

EXTRAP~1_img25

 

Your data has now been extrapolated and you can view it in the extrapolation layer by right clicking it and selecting View Data:

EXTRAP~1_img26

 

EXTRAP~1_img27

 

If you filter out the blanks and do a count you will see there are now 102 744 areas with survey results whereas before we only had

1557:

EXTRAP~1_img28

 

Once all the blanks are filtered out it will also be filtered in the scene and what you can then do is select these areas and create a new layer from that so that you have all surveyed areas in one layer:

EXTRAP~1_img29

 

EXTRAP~1_img30

 

EXTRAP~1_img31

 

 

 

EXTRAP~1_img32

 

EXTRAP~1_img33

 

 

 

 

 

 

 

Support

 

clip0001 

 clip0002

T:  +27871354351

 

support@primethought.biz  - primethought.biz

Kyalami Estate, Midrand, Johannesburg,

1684, South Africa

clip0003clip0004clip0005clip0006clip0007clip0008clip0011