investigation variation/ diversity Flashcards
what is standard deviation
a measure of the spread of the values about the mean
what does a large standard deviation mean
means the values in the sample vary a lot
what does a small standard deviation mean
most of the sample data is around thee mean value
where is the mean in error bar
in the middle
what does a long bar tell us
a larger standard deviation
what is the advantage of using standard deviaiton instead of a range
- SD shows the spread of data around the mean, whilst the range shows the difference between the highest and lowest value.
- SD reduces affects of anomalies whilst range includes anomalies
- SD can be used to identify wether
what does overlapping data show
theres no significant difference
what does non-overlapping data show
the data is significantly different
what is the depemdant variable
variable we measure
where does the independant variable go on a graph
x axis
where does the dependant variable go on a graph
on the y axis
what does a positive r value indicate
positive correlation
when can you use the correlation coefficient
looking to find the strength between thee dependant and independant variable
what is the purpose of a student t test
investigates the difference between two means
what is a paired t test
when both groups have the same sample size
what are the limitations of a student t-test
only used to compare 2 independant data sets
only appropriate when theres no outliers or skew
what is a null hypothesis
theres no relationship between the variables
what does a p value greater than 0.05 suggest
results are due to chance
what happens to the null hypothesis if p is above the critical value
we accept the null hypothesis
if the p value is less than 0.05 what happens to the null hypothesis
we reject the null hypothesis
what does a chi-squared test measure
it measures the difference between the observed and expected value
when chi squared is greater than 0 what does this tell us
theres some difference between the observed and expected results
what cant chi squared tests take
negative values
