# ISA KEY POINTS

GCSE Science AQA (spec B - Written Exams) ISA definitions key points and questions.

## Reliability - Questions

1) What is meant by the term Reliability?

2) How can you make your results more Reliable?

3) Calculate the mean from this set of data? Note; don't forget the step regarding anomolous results.

2cm, 3cm, 2.6cm, 3.1cm, 1.5cm, 1.8cm, 2cm, 17.5cm, 2cm, 2.3cm

4) Name two ways of identifying that results are unreliable.

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## Precision + Accuracy - Questions

1) What is meant by the term Precision?

2) What is meant by the term Accuracy?

3) How can you improve the precision for measuring temperature?

4) I have a list of results. My mean value is 10.5291. The actual Scientific value is 211.5453. I repeated the experiment several times and got the same answer each time. Also i got similar answers to a friend. Describe my result in terms of Accuracy precision and Reliability.

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## Reliability - Answers

1) Repeatable results that follow the general pattern. Also when repeated, results will be the same or similar.

2) Repeating the experiment and getting the same results, Getting somebody else to repeat the experiment and if they get the same result - then this increases reliability.

3) a) discard anomolous (17.5)

b) add remaining values together = 20.3

c) divide by the number of values used = 20.3/9 = 2.26cm

4) Any two from; pattern of results are different from other people, Repeats are widely varying, No pattern seen in results, Results contin an anomolous result.

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## Precision and accuracy - Answers

1) How small a measurement is. Millimeters are more precise than centi-meters because they are smaller.

2) How close the results are to the true value.

3) Use a thermometer with a smaller scale ie. measure to more decimal places. For example instead of measuring to the nearest degree then you could measure to the nearest 0.1 degree.

4) (3 marks)

The results are reliable because you repeated the experiment and got the same result.

The results are precise because the value is measured to 4 decimal places

The results are inaccurate because result is not very close to the true value

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## Errors + Variables - Questions

1) What is a systematic error?

2) What is a random error?

3) What is a continuous variable? What type of graph should be used for this type of data?

4) What is a catergoric variable? What type of graph can be used to represent this type of data?

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## Fair Test - Questions

1) How can you ensure validity? Why?

2) Why do you need to control variables?

3) Name some variables that somtimes can't be controlled?

4) What is a fair test?

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## Errors + Variables - Answers

1) An error caused by; inaccurate equipment, equipment that doesn't "Zero" properly or by a problem in the method.

2) An error caused by things we can't control, such as tiny temperature changes. Also can be caused by human error; pressing button too early ect.

3) A variable that can have any numerical value. Line graphs should be used to represent data.

4) A variable that is described by a label. Bar Charts should be used to represent data.

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## Fair Test - Answers

1) Keep a fair test. To be able to draw a valid conclusion from results.

2) To ensure that the only variable affecting the dependent is the independent.

3) Humidity, Drafts / air movement, tiny temperature changes in room.

4) A fair test is a test in which only one variable (The independent) is allowed to affect the dependent variable. This means only changing the independent and keping all other variable the same.

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## Method + Conclusion - Questions

1) When writing a conclusion about a table of results, what are the 2 things you have to say?

2) When writing a method; how would you get full marks?

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## ISA KEY TERMS

Made By Ben Morris

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## Method + Conclusion - Answers

1) General observation - dependent is affected by independent. Specific observation (- e.g plant x cooled the fastest).

2) Include at least 2 control variables. Mention Repeating the experiment to increase reliability. Say one step in method e.g. measure water into test tube or record starting and end temperature.

3)

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ISA KEY TERMS

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