How Science Works As

Question 1

what is a control experiment for

Answer 1

to compare the results from the real experiment to

to determine that any changes in the dependant variable is directly caused by changes to the independent variable

Question 2

how to treat the control group

Answer 2

treated the same/same drug administered the same

give a dummy/ fake drug/saline/water

Question 3

define control variable

Answer 3

thing you keep the same to ensure an accurate result

Question 4

define independent variable

Answer 4

the thing you change (x axis)

Question 5

define dependant variable

Answer 5

the thing you measure (y axis)

Question 6

examples of control variables

Answer 6

age
sex
ethnicity

Question 7

why have percentages/rates/ratios

Answer 7

allows comparison as they have different populations/starting masses/birth rates ect.

Question 8

how to tell if there are valid results

Answer 8

if nothing has affected the accuracy of the results e.g. how many species, sample size, appropriate temperature/concentration/standard deviation ect.
look for results which don’t follow the pattern and quote them

Question 9

how to comment on correlation

Answer 9

say if there’s a positive or negative correlation
say this might not mean causation
could be due to another factor and give another example
state the points which don’t fit the sample

Question 10

how to avoid bias

Answer 10

no professional/personal investment in conclusion

random choice of people/ sample is more representative

Question 11

why do you need to avoid bias

Answer 11

so everything is random

Question 12

what to do when it says evaluate

Answer 12

give positives and negatives
say what supports the conclusion and what doesn’t
quote data

Question 13

what to do when it says describe

Answer 13

say what you see - completely

quote figures

Question 14

what to do when it says explain

Answer 14

say why something has happened in detail with keywords and phrases

Question 15

what to do when it says suggest

Answer 15

give a sensible based on the information provided
no definitive answer
if you are asked to suggest something, you will generally not have been taught it specifically
you are expected to use the info to give sensible reasons why something may happen

Question 16

how to find unknowns

Answer 16

what variables you would plot
draw a line of best fit
state where you would extrapolate the answer on the graph

Question 17

define standard deviation

Answer 17

spread of data around the mean

Question 18

what does it mean if standard deviations overlap

Answer 18

there is no real difference between the two results

Question 19

what to write if it asks about if there is a significant difference

Answer 19

there is a less than 5% probability that the results are due to chance if there is a real significant difference

Question 20

when to include anomalous

Answer 20

ignore them if they are one of a set of repeated results

otherwise include to reduce the possibility that a key point is being overlooked

Question 21

how to find the uncertainty

Answer 21

plus or minus half the smallest division

Question 22

define precision

Answer 22

little spread about the mean value

depends only on the extent of random errors - it gives no indication of how close the results are to the true value

Question 23

define repeatablility

Answer 23

original experimenter repeats the investigation using the same method and equipment and gets the same results

Question 24

define reproducibility

Answer 24

if the investigation is repeated by another person or different equipment or techniques, and the same results are obtained

Question 25

when to use logarithmic scale

Answer 25

when dealing with really big scales/ranges

Question 26

how to calculate percentage change

Answer 26

change/original x 100

Question 27

define accuracy

Answer 27

close to the true value

Question 28

why to join the dots on the graph

Answer 28

when we don’t know the intermediate values

Question 29

how to increase the accuracy of a investigation

Answer 29

carry out more tests around the estimated value to make the interval smaller
repetitions of each

Question 30

when to use a T-test

Answer 30

looking for a difference between two means

Question 31

when to use a spearman’s rank test

Answer 31

looking for correlation between two continuous sets of data

Question 32

when to used a chi squared test

Answer 32

when looking at frequencies

categoric data, same dependant variable

Question 33

when is a T-test significant

Answer 33

when there is less than a 5% chance that the difference is due to chance

Question 34

when is a spearman’s rank significant

Answer 34

when the correlation is close to + or - 1

Question 35

how to do a chi squared test

Answer 35

compare data with an expected value

difference will be significant or not

Question 36

things to remember making a scientific drawing

Answer 36

no sketchy lines
draw to the left of the page and label to the right of the page
give the scale (magnification)

Question 37

when to use micromols

Answer 37

good for when you are dealing with very small quantities and allows you to avoid using many decimal places