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Evaluating Data

Evaluating Data. Is my data reliable?. Mrs Sharpe likes a nice piece of cod from the fish shop. Two fishmongers ‘Fish R Us’ and ‘Something Fishy’ have signs outside. They both say; Cod average length 30cm £2.50 Mrs Sharpe buys one cod fillet each week and measures them. Fish R Us.

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Evaluating Data

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  1. Evaluating Data

  2. Is my data reliable? • Mrs Sharpe likes a nice piece of cod from the fish shop. • Two fishmongers ‘Fish R Us’ and ‘Something Fishy’ have signs outside. They both say; • Cod average length 30cm £2.50 • Mrs Sharpe buys one cod fillet each week and measures them.

  3. Fish R Us • Length of cod fillet in cm • Week 1: 29cm Week 2: 30cm Week 3: 31cm Average length 30cm • Is the advert for cod fillets 30cm true? Yes the average length of a cod fillet is 30cm • How reliable are Fish R Us? Are the fish all about 30cm long? Quite reliable the average is 30cm and the spread is only 1cm. 1 in 30 is quite small.

  4. Something Fishy • Length of cod fillet in cm • Week 1: 30cm Week 2: 20cm Week 3: 40cm Average length 30cm • Is the advert for cod fillets 30cm true? Yes the average length of a cod fillet is 30cm • How reliable are Something Fishy? Are the fish all about 30cm long? Not very reliable the average is 30cm but the spread is 10cm. 10 in 30 is a lot.

  5. For Example:

  6. Three pieces of data read50 52 48 Work out the average and the spread. How reliable do you think the data is?

  7. Average =50 Spread = 2 • The data is fairly reliable as 2 in 50 is quite small.

  8. Another example:

  9. Three pieces of data read100 105 95 Work out the average and the spread. How reliable do you think the data is?

  10. Average =100 Spread = 5 • The data is fairly reliable as 5 in 100 is quite small.

  11. Another example:

  12. Three pieces of data read85 40 85 Work out the average and the spread. How reliable do you think the data is?

  13. Average =70 Spread = 22.5 • The data is unreliable as 22.5 in 70 is a lot.

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