How Science Works As Flashcards
what is a control experiment for
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
how to treat the control group
treated the same/same drug administered the same
give a dummy/ fake drug/saline/water
define control variable
thing you keep the same to ensure an accurate result
define independent variable
the thing you change (x axis)
define dependant variable
the thing you measure (y axis)
examples of control variables
age
sex
ethnicity
why have percentages/rates/ratios
allows comparison as they have different populations/starting masses/birth rates ect.
how to tell if there are valid results
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
how to comment on correlation
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
how to avoid bias
no professional/personal investment in conclusion
random choice of people/ sample is more representative
why do you need to avoid bias
so everything is random
what to do when it says evaluate
give positives and negatives
say what supports the conclusion and what doesn’t
quote data
what to do when it says describe
say what you see - completely
quote figures
what to do when it says explain
say why something has happened in detail with keywords and phrases
what to do when it says suggest
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
how to find unknowns
what variables you would plot
draw a line of best fit
state where you would extrapolate the answer on the graph
define standard deviation
spread of data around the mean
what does it mean if standard deviations overlap
there is no real difference between the two results
what to write if it asks about if there is a significant difference
there is a less than 5% probability that the results are due to chance if there is a real significant difference
when to include anomalous
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
how to find the uncertainty
plus or minus half the smallest division
define precision
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
define repeatablility
original experimenter repeats the investigation using the same method and equipment and gets the same results
define reproducibility
if the investigation is repeated by another person or different equipment or techniques, and the same results are obtained
when to use logarithmic scale
when dealing with really big scales/ranges
how to calculate percentage change
change/original x 100
define accuracy
close to the true value
why to join the dots on the graph
when we don’t know the intermediate values
how to increase the accuracy of a investigation
carry out more tests around the estimated value to make the interval smaller
repetitions of each
when to use a T-test
looking for a difference between two means
when to use a spearman’s rank test
looking for correlation between two continuous sets of data
when to used a chi squared test
when looking at frequencies
categoric data, same dependant variable
when is a T-test significant
when there is less than a 5% chance that the difference is due to chance
when is a spearman’s rank significant
when the correlation is close to + or - 1
how to do a chi squared test
compare data with an expected value
difference will be significant or not
things to remember making a scientific drawing
no sketchy lines
draw to the left of the page and label to the right of the page
give the scale (magnification)
when to use micromols
good for when you are dealing with very small quantities and allows you to avoid using many decimal places
