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Standardised Numbers

Standardised Numbers. Hayleigh 11B. Standardised Scores. Value - Mean. The Standardised Score =. Standard Deviation.

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Standardised Numbers

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  1. Standardised Numbers Hayleigh 11B

  2. Standardised Scores Value - Mean The Standardised Score = Standard Deviation They are usually based on normal curves which have 68% of the data is in between -1 and +1 standard deviation of the mean. 95% of all values lie between -2 and +2 standard deviations of the mean and 99.7% lie within +/- 3 standard deviations of the mean.

  3. Value - Mean The Standardised Score = Standard Deviation Example The mean and standard deviation of the marks in a Mathematics exam and in a Statistics exam are shown. The marks in both exams are normally distributed. John scored 54 marks in the Maths exam and 57 in the Stats exam. John claimed he was better at Maths. By standardising his marks decide if the data supports his claim. Maths: 54 – 63 6 Stats: 57 – 73 8 This shows that John’s claim is valid because -1.5 is closer to the mean for maths, than -2 is for the mean of stats, so this shows his scores are both lower than the mean and the maths standardised score is closer to the mean therefore indicating a better performance in maths. = -1.5 = -2

  4. Standard Population The standard population usually consists of 1000 people and is a representative sample of the whole population. It is a stratified sample. This means the size of each age group is represented equally. Total = 20414 You should then add the numbers up to check they add up to 1000 which is the size of the sample of the population that is usually required for a standard population.

  5. Example The populations of Liversedge and Outwood are made up as follows: Find the standard population for the towns Add up the total populations. Outwood = 35721Liversedge = 34852 For each age group and each town, divide the population by the total population and x by 1000. Compare the populations of the two towns. You can comment on various things here such as the number of under 16s is higher in Liversedge than in Outwood or that in Liversedge there are less people 61 years or older.

  6. Standardised Birth/Death Rate The standardised death rate is calculated using the standard population of the whole country and the crude rate. This is for each age group and you add them up This is what you are finding out. It is a more accurate measure than the crude rate. (crude rate x standard population) The Standardised Rate = standard population This is the sum of the whole standard population for each age.

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