mvs13I2 X and y are coordinates. They are related to the coordinates on a map. Your point of origin would be the lower left corner of a map, which would make the coordinates (x and y) positive. The scale would depend on how big of an area you are trying to cover. X is the horizontal or West to East, while y is the vertical or South to North.
Hi Cary, really useful, thank you :) Does the model still work if there is a negative x or y coordinate? When I am converting real post / zip codes into coordinates, they are sometimes negative. Thanks.
It will still work with negative x and y coordinates. I am just not sure why you would have a negative zip code. It sounds like you need to do some data cleaning. Typically, the point of origin (x=0 and y=0) is the lower left hand point of the map. Everything is in Quadrant I and the coordinates are relative to that point of origin based on the scale that you are using. As long as the x and y coordinates (data points) are relative to each other and make sense to you, then you could use negative numbers and all four quadrants of a x and y graph. I have seen Center of Gravity models used with perceptual maps (2 dimensions or features associated with a product or service) and these could have negative numbers. You can also do several Center of Gravity models and then overlay them on each other to truly determine location or perception. For location, instead of just using the number of shipments, you could factor in the number of complimentary or associated services, number of employees living in a particular location, busier highways, etc. You can build fairly complex models using very simple approaches.
Hi @@carycountryman thanks so much for replying :) I think I've figured out what it is, I am using the latitude and longitude rather than X and Y, so for example I have an address that is X 446814 Y 241832, but latitude 52.072883 longitude -1.3184022, I guess it's because I'm in England and the meridian line at Grenwich is 0 degrees longitude, so if I am either side of that it affects whether the coordinates are positive or negative. Do I need then to make sure I am using X and Y or should it also work with lat / long? The results I got with those were a little different to what I was expecting, but not massively so.
@@scottwhiffin3578 Sorry it has taken me so long to reply. Since I am no longer in higher education, I don't check this channel as often as I did when I had students taking my courses. I think using latitude and longitude is fine as long as you are not trying to go to global our focusing land masses near the poles. The XY diagram is flat with equal scaling. Latitude and longitude is based on a globe or sphere. Our typical point of origin is the lower left hand corner of a flat map, so that all of our X and Y coordinates are positive (Quadrant 1). Latitude and longitude provides a built in scale and in a way uses all four quadrants of XY diagram. However, the globe is not perfectly flat. As long as you are focuses on smaller region in the center part of the globe you should be okay and not have to make a lot of adjustments. Greenland and Antarctica would require much more of an adjustments because center of gravity model is based on a two dimensional flat map where the distance between lines (horizontal and vertical) are always parallel and equal distance. Perhaps you can figure out what the adjustment needs to be based on the latitude and longitude (what the correction needs to be). That would be a very interesting model for a global scale of gravity.
Thank you! Your demonstration helped me clearly understand this model.
Thank you for this! Very helpful for my business logistics studies.
Thankyou sir, im having a lab test tomorrow about center of gravity and this video helps me alot. Greetings from Indonesia :)
Thanks!
This helped a lot!
Thank you so much!
what do the x and y represent in the table?
mvs13I2 X and y are coordinates. They are related to the coordinates on a map. Your point of origin would be the lower left corner of a map, which would make the coordinates (x and y) positive. The scale would depend on how big of an area you are trying to cover. X is the horizontal or West to East, while y is the vertical or South to North.
Thank you so much
Hi Cary, really useful, thank you :) Does the model still work if there is a negative x or y coordinate? When I am converting real post / zip codes into coordinates, they are sometimes negative. Thanks.
It will still work with negative x and y coordinates. I am just not sure why you would have a negative zip code. It sounds like you need to do some data cleaning. Typically, the point of origin (x=0 and y=0) is the lower left hand point of the map. Everything is in Quadrant I and the coordinates are relative to that point of origin based on the scale that you are using. As long as the x and y coordinates (data points) are relative to each other and make sense to you, then you could use negative numbers and all four quadrants of a x and y graph. I have seen Center of Gravity models used with perceptual maps (2 dimensions or features associated with a product or service) and these could have negative numbers. You can also do several Center of Gravity models and then overlay them on each other to truly determine location or perception. For location, instead of just using the number of shipments, you could factor in the number of complimentary or associated services, number of employees living in a particular location, busier highways, etc. You can build fairly complex models using very simple approaches.
Hi @@carycountryman thanks so much for replying :) I think I've figured out what it is, I am using the latitude and longitude rather than X and Y, so for example I have an address that is X 446814 Y 241832, but latitude 52.072883 longitude -1.3184022, I guess it's because I'm in England and the meridian line at Grenwich is 0 degrees longitude, so if I am either side of that it affects whether the coordinates are positive or negative.
Do I need then to make sure I am using X and Y or should it also work with lat / long? The results I got with those were a little different to what I was expecting, but not massively so.
@@scottwhiffin3578 Sorry it has taken me so long to reply. Since I am no longer in higher education, I don't check this channel as often as I did when I had students taking my courses. I think using latitude and longitude is fine as long as you are not trying to go to global our focusing land masses near the poles. The XY diagram is flat with equal scaling. Latitude and longitude is based on a globe or sphere. Our typical point of origin is the lower left hand corner of a flat map, so that all of our X and Y coordinates are positive (Quadrant 1). Latitude and longitude provides a built in scale and in a way uses all four quadrants of XY diagram. However, the globe is not perfectly flat. As long as you are focuses on smaller region in the center part of the globe you should be okay and not have to make a lot of adjustments. Greenland and Antarctica would require much more of an adjustments because center of gravity model is based on a two dimensional flat map where the distance between lines (horizontal and vertical) are always parallel and equal distance. Perhaps you can figure out what the adjustment needs to be based on the latitude and longitude (what the correction needs to be). That would be a very interesting model for a global scale of gravity.
@@carycountryman no problem at all, and thank you for getting back to me!
thank you for explen this
This is off-topic, but Natchitoches is pronounced "Nackedish".