statistics Flashcards
how many main types of statistics are there and what are they
- Measuring the spread (standard deviation), and statistical tests.
what does descriptive statistics involve
range and standard deviation from mean
when would you use a statistical test
to allow what we do know to make judgements about what we don’t know
how many types of statistical tests are there and what are they called
- Chi squared, student’s t-test, spearman’s rank
in a test will you be asked to perform a calculation
no but you will need to know how the answer was recieved
what is the formula for range
range= largest value - smallest value
sometimes we can’t use the range why
because there are outliers therefore its not a good measure of the spread.
what is the range used for
a type of measurement to calculate the spread
what does standard deviation mean
measure of how spread out all your repeats are from your mean
why is using standard deviation better than using the range
because SD looks at the spread of data around mean and its less affected by outliers
what does a high and low standard deviation look like
low- thin curve
high- fat curve
what does a thin curve mean
that most values remain close to the average and the standard deviation is small
what does a fat curve mean
that there is a wider spread of data around the mean, standard deviation is large
what will a normal standard deviation graph look like
a bell- shaped graph
what is the percentage of data that is within 1 standard deviation either side of the mean
over 68%
what is the percentage of the data that is within 2 standard deviations
95%
what is chi squared test also known as
X squared
how can we describe the results on graph
we can draw a bar chart and plot the 2 standard deviations from the mean
what does an overlap mean
it is likely due to chance and they are not significantly different
how will you know to choose chi squared test
ASSOCIATED WITH FREQUENCIES-frequencies- does the investigation involve finding numbers of individuals in a particular categories?
what does a no overlap mean
unlikely due to chance and they are significantly different
how will you know to do a students t-test
LOOK FOR A MEAN-does your investigation involve taking measurements? will your investigation involve looking for differences between mean values?
how will you know to do a spearman’s rank test
does your investigation involve taking measurements? are you looking for associations between different measurements from the same sample?A CORRELATION
how do you write a null hypothesis for X 2 test
There is no significant difference between the number of …
how do you write a null hypothesis for a t test
There is no significant difference between the mean number of…
how do you write a null hypothesis for spearmans rank
There will be no correlation between the … and ….
