PLAN

I am going to investigate the IQ’s and number of hours of TV watched a day of students between 11 and 16 years old.

To do this I am going to use a spreadsheet of data about the pupils in a large school. The spreadsheet has all students in alphabetical order. As I want to see how IQ and number of hours of TV watched a day changes with age I will order the students by year groups and by gender.

My Sample

I have decided to look at years 7 and 11. I will take equal numbers of boys and girls in each year group so that I can compare boys’ results with girls’ results.

I will use the method of random sampling so that everyone in the group has an equal chance of being selected and to remove any possibilities of bias.

I want a total sample of 60, so I will take a sample of 15 boys and 15 girls from each year group to make 30 in each year.

In year 7 there are 131 girls. I want a sample of 15. I will use a calculator to get my random numbers. I will read off 3 digit numbers until I have 15 different numbers between 001 and 131. These will give me my sample of girls.

My random numbers are:-

051, 096, 025, 092, 129, 016, 128, 090, 085, 108, 131, 064, 089, 068, 057

Because there are 151 boys I cannot use the same set of numbers for the boys as it would not allow the last 20 students to be selected. Therefore I will get random numbers in the same way for the boys but until I have 15 different random numbers between 001 and 151.

My random numbers are:-

078, 136, 131, 019, 080, 059, 009, 103, 061, 141, 031, 021, 088, 044, 015

I will then repeat this process for year 11 but only read of 2 digit numbers between 01 and 86 for the girls and between 01 and 84 for the boys.

My random numbers for the girls are:-

58, 51, 49, 37, 62, 32, 38, 27, 42, 84, 33, 72, 65, 13, 06

My random numbers for the boys are:-

44, 34, 83, 17, 75, 47, 84, 46, 67, 54, 57, 02, 58, 73, 63

When I have obtained my samples I will use the computer to order the data to help me find medians and quartiles etc.

Hypotheses

- There is a strong correlation between the number of hours of TV watched a day and the IQ.
- Girls in year 11 have a higher IQ than girls in year 7.
- Boys in year 7 watch more TV than boys in year 11.

Method of Analysing My Data

Using my ordered lists I will first find medians and quartiles and draw box plots for each year group in my sample on the same axes and to the same scale so that I can compare them.

When I have drawn the box plots, it will be clear whether there are any outliers in my data. If there is an outlier I will decide if someone is just abnormal or if there is a mistake in the data. If it is a mistake then I will ignore it and have one less piece of data.

I will then draw scatter grams to see whether there is any correlation between IQ and number of hours of TV watched a day. If there is any correlation I will draw a line of best fit which I can use to make predictions. I will draw separate scatter grams for the two year groups but using the same scale so that I can compare them properly.