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Stratified Sampling

Stratified Sampling. Objective: To be able to use stratified sampling methods to find a suitable sample size Grade A. Easy Stratified Sampling. The table shows the number of pupils in each year. I want to take a stratified sample of 10% people. How many pupils will I need from each Year?.

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Stratified Sampling

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  1. Stratified Sampling Objective: To be able to use stratified sampling methods to find a suitable sample size Grade A

  2. Easy Stratified Sampling The table shows the number of pupils in each year I want to take a stratified sample of 10% people. How many pupils will I need from each Year? Year 7: 10% x 320 = 32 Year 8: 10% x 311 = 31.1 31 Year 9: 10% x 380 = 38 Year 10: 10% x 289 = 28.9 29 Year 11: 10% x 300 = 30

  3. Stratified Sampling The table shows the number of pupils in each year I want to take a stratified sample of 250 people. How many pupils will I need from each year? Add up the totals 320 + 311 + 380 + 289 + 300 = 1600

  4. Stratified Sampling The table shows the number of pupils in each year I want to take a stratified sample of 250 people. How many pupils will I need from each year? So, we need a sample of 250 out of a possible 1600 This is our sample size: 250 1600

  5. Stratified Sampling The table shows the number of pupils in each year 320 I want to take a stratified sample of 250 people. How many pupils will I need from each year? Year 7: Year 8: Year 9: Year 10: Year 11: Sample Size: 250 × = 50 1600

  6. 48.4375 Stratified Sampling The table shows the number of pupils in each year 311 I want to take a stratified sample of 250 people. How many pupils will I need from each year? Year 7: 50 Year 8: Year 9: Year 10: Year 11: Sample Size: 250 × = 49 48.59375 1600

  7. 48.4375 Stratified Sampling The table shows the number of pupils in each year 380 I want to take a stratified sample of 250 people. How many pupils will I need from each year? Year 7: 50 Year 8: 49 Year 9: Year 10: Year 11: Sample Size: 250 × = 59 59.375 1600

  8. 48.4375 Stratified Sampling The table shows the number of pupils in each year 289 I want to take a stratified sample of 250 people. How many pupils will I need from each year? Year 7: 50 Year 8: 49 Year 9: 59 Year 10: Year 11: Sample Size: 250 × = 45 45.15625 1600

  9. 48.4375 Stratified Sampling The table shows the number of pupils in each year 300 I want to take a stratified sample of 250 people. How many pupils will I need from each year? Year 7: 50 Year 8: 49 Year 9: 59 Year 10: 45 Year 11: Sample Size: 250 × = 46.875 47 1600

  10. 48.4375 Stratified Sampling The table shows the number of pupils in each year I want to take a stratified sample of 250 people. How many pupils will I need from each year? We needed a stratified sample of 250 people Year 7: 50 Year 8: 49 Year 9: 59 Year 10: 45 Year 11: 47 Check: 50 + 49 + 59 + 45 + 47 = 250

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