My purpose is to see if there is any relationship between the height and diameter at breast height (DBH) in podocarp trees. My response variable is the DBH and my explanatory variable is height. All of my data comes from a random sample collected from the Waitutu Forest during 2001-2008.
By looking at this graph, I can see that there appears to be a clear linear trend with a positive relationship. Therefore, it would be sensible to use a linear regression model to investigate the relationship. This shows that as the height of the saplings increases, so does the diameter of the saplings at breast height. The rate of increase is not consistent, and the spread of the data increases as the podocarp height does.
An interesting point to note …show more content…
This reinforces the linear trend and positive relationship between the height of a podocarp sapling and its DBH in this model. The spread appears uneven with a strong relationship for shorter podocarps but weaker for taller podocarps - DBH values are further apart for taller trees. This may be due to the different rates at which different species of podocarps (rimu, miro, totara) grow. Overall, the strength of the relationship appears to be strong. This is further reinforced by the r value of 0.81887 which indicates a strong …show more content…
Since the linear line appears to fit the model reasonably well, I will use this to make my prediction. For my prediction, i substituted the heights into: dbh=0.070203xH-3.9176 dbh=0.070203x200-3.9176 dbh=0.070203x200-3.9176=10.123 which is near the middle of the data points of the DBH values.
Because the strength of the relationship is strong here, I would say that this prediction is quite reliable.
dbh=0.070203xH-3.9176 dbh=0.070203x500-3.9176 dbh=0.070203x500-3.9176=31.1839 which is right in the middle of the data points of the DBH values.
Because the relationship is weaker here I would not say that this prediction is completely reliable.
Conclusion
The analysis indicates that the DBH of podocarp saplings in the WAItutu Forest tends to increase as the height increases. The relationship is strong but tends to become weaker as the height increases. The DBH of podocarp saplings could be 20-30 cm larger or smaller than what the model predicts. The model is based on datasets from Waitutu Forest, collected from 2001-2008.
Bibliography
http://collections.tepapa.govt.nz/topic/1446
By looking at this graph, I can see that there appears to be a clear linear trend with a positive relationship. Therefore, it would be sensible to use a linear regression model to investigate the relationship. This shows that as the height of the saplings increases, so does the diameter of the saplings at breast height. The rate of increase is not consistent, and the spread of the data increases as the podocarp height does.
An interesting point to note …show more content…
This reinforces the linear trend and positive relationship between the height of a podocarp sapling and its DBH in this model. The spread appears uneven with a strong relationship for shorter podocarps but weaker for taller podocarps - DBH values are further apart for taller trees. This may be due to the different rates at which different species of podocarps (rimu, miro, totara) grow. Overall, the strength of the relationship appears to be strong. This is further reinforced by the r value of 0.81887 which indicates a strong …show more content…
Since the linear line appears to fit the model reasonably well, I will use this to make my prediction. For my prediction, i substituted the heights into: dbh=0.070203xH-3.9176 dbh=0.070203x200-3.9176 dbh=0.070203x200-3.9176=10.123 which is near the middle of the data points of the DBH values.
Because the strength of the relationship is strong here, I would say that this prediction is quite reliable.
dbh=0.070203xH-3.9176 dbh=0.070203x500-3.9176 dbh=0.070203x500-3.9176=31.1839 which is right in the middle of the data points of the DBH values.
Because the relationship is weaker here I would not say that this prediction is completely reliable.
Conclusion
The analysis indicates that the DBH of podocarp saplings in the WAItutu Forest tends to increase as the height increases. The relationship is strong but tends to become weaker as the height increases. The DBH of podocarp saplings could be 20-30 cm larger or smaller than what the model predicts. The model is based on datasets from Waitutu Forest, collected from 2001-2008.
Bibliography
http://collections.tepapa.govt.nz/topic/1446