rUGBY EX
rugby report
[Not needed for achieved]
From what I know about rugby, the players in the forward pack, are usually bigger than the backs. This is because a strong scrum can dominate and win rugby games. The forwards in the pack also are involved in high impact as they push the ball towards their opponents. They need to be strong and big to sustain the damage inflicted by the opposition. A lot of injuries result from forward players. The wingers are known for their speed. Forwards are getting bigger and heavier, a key winning element to match success.
From what I know about rugby, the players in the forward pack, are usually bigger than the backs. This is because a strong scrum can dominate and win rugby games. The forwards in the pack also are involved in high impact as they push the ball towards their opponents. They need to be strong and big to sustain the damage inflicted by the opposition. A lot of injuries result from forward players. The wingers are known for their speed. Forwards are getting bigger and heavier, a key winning element to match success.
Problem:
I wonder if rugby players in the forward position tend to be heavier than rugby players in the back position. I will investigate this using a random sample of 135 male rugby players from New Zealand and South Africa in the NZGrapher data base. The data set comes from https://www.rugbyhow.com/ and is dated 2012/13. There are 59 backs and 76 forwards in the data set. This information could be useful for anyone wanting to put together a rugby team for a competition.
I wonder if rugby players in the forward position tend to be heavier than rugby players in the back position. I will investigate this using a random sample of 135 male rugby players from New Zealand and South Africa in the NZGrapher data base. The data set comes from https://www.rugbyhow.com/ and is dated 2012/13. There are 59 backs and 76 forwards in the data set. This information could be useful for anyone wanting to put together a rugby team for a competition.
Plan:
The variable I will investigate are the weights of male rugby players who have professionally represented New Zealand and South Africa in rugby over the 2012/2013 season. The unit of measurement is the kg. I will use total of 135 random samples from the NZGrapher database.
This is a good sample size (30 would be a minimum sample size) to use for my investigation to determine if players in the forward position tend to be heavier than players in the back position back in the greater population of rugby players including Australia, Argentina and the northern hemisphere teams as well.
I will use NZGrapher to make a comparative box and whisker plot with dots. I will also produce a summary of statistics for my sample. This will allow me to make the call back in the population of Rugby players whether the forwards tend to be heavier than the backs who have represented South Africa and New Zealand in the professional rugby era.
The sample of 135 players was randomly chosen so my conclusion should be valid in this investigation.
.
The variable I will investigate are the weights of male rugby players who have professionally represented New Zealand and South Africa in rugby over the 2012/2013 season. The unit of measurement is the kg. I will use total of 135 random samples from the NZGrapher database.
This is a good sample size (30 would be a minimum sample size) to use for my investigation to determine if players in the forward position tend to be heavier than players in the back position back in the greater population of rugby players including Australia, Argentina and the northern hemisphere teams as well.
I will use NZGrapher to make a comparative box and whisker plot with dots. I will also produce a summary of statistics for my sample. This will allow me to make the call back in the population of Rugby players whether the forwards tend to be heavier than the backs who have represented South Africa and New Zealand in the professional rugby era.
The sample of 135 players was randomly chosen so my conclusion should be valid in this investigation.
.
Data:
Analysis:
Initial indications from the graph show a considerable difference between the players in the back and forward positions. I think my investigation will reveal that on average, forwards are heavier than backs.
Central Tendency:
The median weight for players in the forward pack is 110.5 kg and the median weight for players in the backs is 92 kg, a difference of 18.5 kg. This indicates that the forward players could be heavier on average than backs back in the wider population of international rugby players from both hemispheres. This makes sense as the larger heavier players tend to suit forward positions because rugby is a very confrontational game and the forwards clear the way for the backs to participate in the match. Forward packs are also capable of scoring by themselves and entire packs are known to push back their opponents across their own lines and score tries. Their heavy mass makes this achievable.
Spread:
The IQR (middle 50%) for the forward pack is 12.5 kg whereas the IQR (middle 50% ) for backs is 8 kg. This indicates that there is more variation in the weights of forward players which means there are many players of differing weights. This could be quite useful as players with different physical characteristics could be used to create a good scrum formation. The heavier players would be good for their pushing power, and some forwards are smaller like in hookers. The lighter players would be good in moving the ball out to the backs because they are lighter and faster. In the backs the players are more similar in weight and tend to be lighter. They also tend to be faster. Overall visually looking at the dot plot, the forward pack are more spread out than the backs. I would expect similar statistics to be seen in the wider population of rugby players in New Zealand and South Africa.
Shift:
The box (middle 50%) for the forward pack is further shifted to the right of the box (middle 50%). for the backs. The lower quartile of the forward pack weights (104.5 kg) is higher than the upper quartile for the weight of the backs (96 kg). This also indicates there is no overlap of the middle 50% (IQR) for forwards and backs in the sample of rugby players. This also indicates the fact that the players making up the forward packs in rugby are indeed heavier than the players that make up the back positions. This is important in the game as a team with large heavy players can dominates scrums and generally push their way through the opposition on attack and have stopping power in defence in tackling and blocking.
Shape:
The distribution of the weights of the backs is relatively symmetrical because the tails on the left and right are about the same length on the dot plot. The forward pack weights show some right skewing of the data which spreads out towards the most heaviest player. There are two players in the backs which are the heaviest at 105 kg. The heaviest forward is 137 kg. It makes sense as we want the forwards to have punching power in the attack and remain solid in defence. I think the distributions of weights of forwards and backs would also be nearly similar in the population of All Black and Springbok players with the lightest and heaviest players causing the left and right skewing of the data. Looking at the distribution of the backs there are 13 players of a similar weight which explains why the middle 50% is not as spread out as the forward pack players.
Unusual features:
Looking at the graphs I can see that the forwards have one player that weighs more than all others in the forward pack. The player is listed as weighing 137 kg and at 181 cm in height this seemed a bit suspect. Loosehead prop Karl Tu'inukuafe was the heaviest 2018 All Black at 135kg and 182 cm in height so its quite possible its a genuine sample. Brodie Retallick (123kg/2.04cm) and Owen Franks (119kg/1.85cm) come close with Sam Whitelock, but they are also some of the tallest players in the forward pack.
There are two backs weighing 105kg which could fit into the box (middle 50%) of the forward pack. This makes sense if they are big because they could be fast at running with the ball. A big heavy fast runner would be an asset in any team. One of them is 1.84m which means they could be a forward looking at the data set, but for some reason perhaps their skill level keeps them in the back position.
The smallest player sample is in the backs and is a South African player who is quite tall at 1.85m weighing only 77 kg.
There are two backs weighing 105kg which could fit into the box (middle 50%) of the forward pack. This makes sense if they are big because they could be fast at running with the ball. A big heavy fast runner would be an asset in any team. One of them is 1.84m which means they could be a forward looking at the data set, but for some reason perhaps their skill level keeps them in the back position.
The smallest player sample is in the backs and is a South African player who is quite tall at 1.85m weighing only 77 kg.
Overlap:
Although the boxes don't overlap, there are a number of players that share a common weight between both backs and forwards. This is where the heavier backs are 'overlapping' the lighter forwards. This could be useful because it might be possible to exchange roles within the team. These players of similar weight are called utility players because they can be involved in more than one position. However, because I they are big, they are probably tall as well.
Conclusion:
The graph shows that the average weights for forward players is greater than the average weight for backs in this data set representing the population of players for South Africa and New Zealand. The dbm/ovs ratio is 18.5/29 = 0.64 and since this is greater than 1/3 I can make the call that the players in the forward pack tend to be on average heavier than the players in the backs. This is confirmed by the median values in the summary statistics above. The median weight for the forwards is 110.5 kg and the median weight for the backs is 92kg.
I used the median values in determining the outcome of the investigation since the results are not influenced by extreme values. In this case, because the shape of the graphs for backs and forwards are nearly symmetrical, the median and means are not too far from each other. The forwards are bigger and heavier than the backs so they can work their way up the field to score tries. They are chosen for this roll because of their size which is determined by their genetics they got from their parents.
Based on looking at my sample and graph I am reasonably confident that the median weight of forwards tends to be greater than the median weight of the backs. The distance between the medians compared to the overall visible spread is greater than one third. Forwards tend to be heavier on average than backs back in the population of International rugby players.
I am reasonably confident about this call but I might get a different answer if I took another sample. Another sample would have different data points and would produce different graphs that could lead me to a different answer, although I think this is very unlikely. It is unlikely because of the big shift between the medians in my samples and the high value of the DBM/OVS ratio.
Improvements on the investigation:
I think that this investigation could have been more reliable if we were to have a larger sample size. The sample size of 135 is considered to be reasonably large enough to represent the population of rugby players available. However, I could collect more data. For example I could investigate the forward and back positions of other rugby playing nations to improve the accuracy of our investigation such as Argentine, Australia, Japan and the Northern hemisphere teams. If we had a larger sample size, I would have more confidence in the conclusion I have made that forwards are heavier than backs in the All Black and South African teams.
Another kind of investigation that could be done would be to see which country has the heaviest forward and back pack. Sometimes certain countries have a reputation for having a heavy scrum weight compared to their competitors. Since the All Blacks win so many games, could it be possible our players are simply bigger on average than other teams? I don't know if its a factor but it would be interesting to explore.
The number of data entries for forwards and backs is not the same. There are 59 backs and 79 forwards. To represent the players more accurately we could have used a sample that contains the same number of forwards and backs in the sample.
Who might find this investigation useful?
This data could be of importance to anyone interested in the game of rugby such as coaches, managers and schools. This could be useful in choosing their position in a particular code. Tall heavier students for the forwards and the lighter faster students in the backs.
I think that this investigation could have been more reliable if we were to have a larger sample size. The sample size of 135 is considered to be reasonably large enough to represent the population of rugby players available. However, I could collect more data. For example I could investigate the forward and back positions of other rugby playing nations to improve the accuracy of our investigation such as Argentine, Australia, Japan and the Northern hemisphere teams. If we had a larger sample size, I would have more confidence in the conclusion I have made that forwards are heavier than backs in the All Black and South African teams.
Another kind of investigation that could be done would be to see which country has the heaviest forward and back pack. Sometimes certain countries have a reputation for having a heavy scrum weight compared to their competitors. Since the All Blacks win so many games, could it be possible our players are simply bigger on average than other teams? I don't know if its a factor but it would be interesting to explore.
The number of data entries for forwards and backs is not the same. There are 59 backs and 79 forwards. To represent the players more accurately we could have used a sample that contains the same number of forwards and backs in the sample.
Who might find this investigation useful?
This data could be of importance to anyone interested in the game of rugby such as coaches, managers and schools. This could be useful in choosing their position in a particular code. Tall heavier students for the forwards and the lighter faster students in the backs.