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Flashcards in Maths Deck (19):
1

Percentage error =

Uncertainty
-------------- X 100
Reading

2

Uncertainty value?

Half the smallest graduation e.g. on a ruler with 1mm graduations it would be 0.5mm

3

Margin of error?

Uncertainty value double e.g. On a ruler with 1mm graduations the margin of error would be 1mm

4

Sampling bias?

You unintentionally avoid areas of your potential sample e.g. Muddy areas.

5

Chance?

Even without bias it may not have been representative as it is impossible to test every single thing.

6

Why won't things be representative?

- sampling bias
- chance

7

Ways to avoid sampling bias?

- random sampling e.g. Random coordinates.
- using a larger sample, less chance of chance effect the results.
- analysis of data collected e.g. Stats tests, mode, median, mean and standard deviation.

8

Standard deviation?

Measuring variation from the mean in a sample. Smaller standard deviations results more clustered data which means less extreme values so it is more reliable. Standard deviation is a good measure of the reliability of the mean.

9

Normal distributions of standard deviation?

Standard deviation valve is smaller for A than B so the smaller the spread of data around mean A which is therefore a more reliable mean.

10

Binomial distribution, comparing two standard deviations?

Standard deviation value for A is smaller than B so smaller spread of data around mean A which is therefore a more reliable mean. No overlap between standard deviations means there is a significant difference between the two means.

11

Rate of reaction =

Y
----
X

12

Chi squared?

Null hypothesis: no significant difference in NUMBER
Appropriate table: normal two headed table
How to present data: bar chart

13

Student T test?

Null hypothesis: no significant difference in MEAN
Appropriate table: table with mean column
How to present data: bar chart with standard deviation bars

14

Spearmans Rank?

Null hypothesis: no significant difference in CORRELATION
Appropriate table: pairs of data in table
How to present data: scatter gram

15

At p = 0.01 to p = 0.05

Reject the null and accept the experimental as there is a significant difference

16

At p = 0.06 and above

Accept the null hypothesis and reject the experimental hypothesis as there is not a significant difference

17

What are the three stats tests?

Chi squared , student t test and spearmans rank.

18

Volume of solute needed =

Concentration you want
------------------------------- X total volume you want
Concentration you've got

19

Magnification =

Image size
--------------
Actual size

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