# During my plan I will be trying to find out whether girls area taller than boys when entering secondary school in year 7 and who out of the two is taller when leaving secondary school in year 11. I choose this enquiry

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Introduction

Data Handling Coursework

Introduction

- Random sampling

Random sampling is a sampling technique where you select a group of subjects (a sample) for study from a larger group (a population) where each individual is chosen entirely by chance and each value in the data has a known, but possibly non-equal, chance of being included in the sample. By using random sampling, the likelihood of bias is reduced.

- Systematic sampling

Systematic sampling follows a similar approach to random sampling as all the values chosen are selected entirely by chance and each have an equal and equivalent chance of being chosen, but apart from this systematic sampling differs as unlike random sampling, systematic sampling uses a methodical and logic selection technical to sampling e.g. every second value is chosen in the data.

- Cluster sampling

Cluster sampling is a sampling technique where the entire population is divided into groups, or clusters and a random sample of these clusters are selected. All observations in the selected clusters are included in the sample. Cluster sampling is typically used when the researcher cannot get a complete list of the members of a population they wish to study but can get a complete list of groups or 'clusters' of the population. It is also used when

Middle

9

120

140

260

(260/1200)*50 = 11

(120/260)*11 = 5

(140/260)*11 = 6

10

100

100

200

(200/1200)*50 = 8

(100/200)*8 = 4

(100/200)*8 = 4

11

84

86

170

(170/1200)*50 = 7

(84/170)*7 = 3

(86/170)*7 = 4

Total

1200

50

25

26

We can see in the scatter graph above that there is a large negative collection between BMI and height meaning that as height increases BMI decreases which prove my prediction that as BMI will decrease as height increases. I believe this comes as a result of height being the denominating factor in the equation to calculate BMI therefore if you are increasing the height the BMI wall fall.

We can see in this scatter graph that there has been a similar outcome to that of the girls although the negative correlation isn’t as big, I believe this is because even though if you increase height the BMI should fall weight is still a factor and if the weight is already high the BMI wouldn’t fall as quickly as it should especially if everyone is heavy and of similar weight.

With this scatter graph involving weight rather than height we can see that there is a positive correlation indicating that as weight increases so does BMI which I have announce in my prediction this is because weight is the numerating faction in the equation to calculate BMI and therefore as it increases BMI also increases since the numerator is increasing while the denominator stays the same making the result of the equation, the BMI, bigger.

This same theory about increasing weight directly increases BMI applies to this scatter graph as well since we can see as the boys weights increased so did the BMI.

In the scatter group above we can see that for girls as the grow order (increasing year group) there BMI decrease as you can see a negative correlation between BMI and year group on the scatter graph above. I believe this to be a result of girls either getting taller or losing weight as they grow up as these are the two variable involved in calculating BMI.

However for the boys in the scatter graph above there seems to be a small positive correlation between year group and BMI meaning that the boys as they are getting older are getting heavier since they cannot get shorter to increasing their BMI.

- Girls

BMI for girls | Frequency(f) | BMI | Cumulative Frequency | Mid-value (x) | fx | Fx2 |

10<15 | 3 | <15 | 3 | 12.5 | 37.5 | 468.75 |

15<20 | 11 | <20 | 14 | 17.5 | 192.5 | 3368.75 |

20<25 | 9 | <25 | 23 | 22.5 | 202.5 | 4556.25 |

25<30 | 2 | <30 | 25 | 27.5 | 55 | 1512.5 |

Total | 25 | 487.5 | 9906.25 |

Conclusion

Conclusion

In conclusion I have found out from carrying this enquiry that the boys were naturally taller than the girls, which can be seen in the scatter graphs I carried out in my plan. From this I used the knowledge I gained and changed the enquiry slightly to find out whether boys had a bigger BMI than girls since I knew that boys were taller but also heavy so I wanted to find out whether they will still have a bigger BMI than girls since they are taller and height reduces BMI while weight increases BMI.

Derrick Gachiri

This student written piece of work is one of many that can be found in our GCSE Height and Weight of Pupils and other Mayfield High School investigations section.

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