S1 Exploring Data Flashcards
What is qualitative data?
Things that aren’t numbers. Eye colour, favourite flavour of something. Can be shown in pie charts and bar charts.
What are the types of data?
Categorical or qualitative
Numerical or quantitive
What is quantitive data?
It is in numbers. It is more useful as it allows you to work out averages and measures of spread.
There is continuous and discrete data.
Explain the difference between continuous and discrete data.
Continuous. Any value in a range. Something that you measure.
Discrete. Only takes set values. Something you count.
What is a distribution?
The shape of the data when draw on a frequency graph.
What are the types of skew.
A positive skew is when the data is skewed towards the Y axis. Towards 0.
Negative skew is when the data to skewed to the right. Towards the larger numbers.
What would a bimodal distribution look like?
There would be 2 lumps in it. Like a camel.
What does unimodal mean?
There is one large lump.
What is a uniform distribution?
Where everything is roughly the same value.
What is the advantage and disadvantage of using the mean?
It takes into account all the data. However it can be skewed by extreme values.
How do you find the mid range?
Add the largest and the smallest value together and divide by 2.
What is the inter quartile range?
It is the range of the middle 50% of values.
How is S”xx” found?
Square each value and multiply by its frequency. Add together.
Get the mean and square it. Multiply by the total frequency(not the sum of the squared frequency). Take this away from the sum of the first numbers.
How is the SD found using S”xx”?
Find the square root of S”xx” divided by one less than the total frequency.
If you were simply provided with a long list of numbers, how would you find the S”xx”?
Just square all the numbers and add them together and minus the mean² times the number of the numbers.
What is an outlier?
A value more than 2 SD away from the mean?
What is done with outliers ?
They are investigated. If there are true, they are included.
What does the table of a probability distribution show?
The probability of different outcomes. There should add up to one.
How is expectation calculated?
Multiply the P of a result by the result its self. Then add together.
How is variance calculated?
Square the different results and multiply by the probabilities. Add together.Then minus the square of the expectation.
How can variance be calculated with the standard deviation?
Square the standard deviation.
What is the symbol for standard deviation?
Sigma.
What is the symbol for expectance ?
u
What does X~B(n,p)mean?
The event Xis binomial distributed.
p is the probability.
n is the number of events.