rugby 2022
Assessment practice
Using the database on Rugby players from NZGrapher, investigate the relationship between the height and weight of players in the game.
PROBLEM
I recently watched the Springboks play the All Blacks at Eden Park. I noticed there are quite a variety of player sizes in the game of Rugby.
My Question is: I wonder if there is a relationship between the height and weights of NZ and South African rugby players. I think the taller players will be heavier.
The source of information comes from www.rugbyhow.com and the data set is from NZGrapher.
I recently watched the Springboks play the All Blacks at Eden Park. I noticed there are quite a variety of player sizes in the game of Rugby.
My Question is: I wonder if there is a relationship between the height and weights of NZ and South African rugby players. I think the taller players will be heavier.
The source of information comes from www.rugbyhow.com and the data set is from NZGrapher.
PLAN
The Explanatory (independent) variable is the height of rugby players in metres. The response (dependent) variable is the weight of rugby players in kg. I chose height for the explanatory variable because I think that this will have the strongest influence and most direct relationship with the weight.
The Explanatory (independent) variable is the height of rugby players in metres. The response (dependent) variable is the weight of rugby players in kg. I chose height for the explanatory variable because I think that this will have the strongest influence and most direct relationship with the weight.
ANALYSIS
Referring to the graph above there appears to be a positive linear trend. Because the trend appears to be linear, I will fit a linear
regression line to investigate this further. This means that taller rugby players TEND to weigh more.
Referring to the graph above there appears to be a positive linear trend. Because the trend appears to be linear, I will fit a linear
regression line to investigate this further. This means that taller rugby players TEND to weigh more.
Trend
Looking at the linear regression line I notice that the data points form a linear band of data points.
Association
I can see that the association is positive because as the heights of the players increase, the weight of the players also tends to increase. That is, the taller the player, the heavier they are.
Strength
The strength of the relationship is moderate to weak since the data points are reasonably scattered above and below the trend line.
Groups
I don't notice any particular grouping in the data set. All the data points appear evenly spread across the regression line. However, there are three players who are shorter and lighter than the others in the data set.
Unusual Data
I don't see anything unusual in the data set in terms of outliers but many players of the same height have different weights. So there is a lot of variety in the data.
Scatter
The scatter is consistent across the data set in the graph
Confidence in the Regression LineThe linear regression line gives us the average increase over the whole graph. The equation for the regression line:
Weight = 66.726 x height - 21.866
This means that for each increase in height of 1m, the weight of a player approximately increases by about 66.726kg. Based on my linear regression line I would predict that a player with a height of 2m would weigh about:
W = 66.726 x 2 - 21.866 = 111.59kg
There are a few data points above and below this value so I am confident the prediction is reliable.
Conclusion
I can conclude that taller players tend to weigh more than shorter players in the data for NZ and South African rugby players.
Weight = 66.726 x height - 21.866
This means that for each increase in height of 1m, the weight of a player approximately increases by about 66.726kg. Based on my linear regression line I would predict that a player with a height of 2m would weigh about:
W = 66.726 x 2 - 21.866 = 111.59kg
There are a few data points above and below this value so I am confident the prediction is reliable.
Conclusion
I can conclude that taller players tend to weigh more than shorter players in the data for NZ and South African rugby players.