Maths- statistics 1
- Created by: shona
- Created on: 26-12-12 16:13
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- Maths- statistics 1
- averages and range
- mode
- most common
- median
- the middle number once arranged in order
- mean
- the sum of all values divided by the total number of values in the set
- mean= sum of all values/ total number of values
- the sum of all values divided by the total number of values in the set
- range
- the difference between the highest and lowest values in a set
- range= highest-lowest
- the difference between the highest and lowest values in a set
- mode
- frequency tables
- when data is represented it can be put in a frequency table
- find the mode by looking for the data value that has the highest frequency
- find the median by adding up all the frequencies in order until half way point of all data is passed
- find the mean by multiplying the value of each data by its frequency adding the totals and dividing by the total of all the frequencies
- grouped data and frequency diagrams
- when there is a wide range of data with lots of values there are often too many entries for the frequency table
- so you will use a grouped frequency table
- in a grouped frequency table data is recorded in groups like 10< x<20
- grouped data can be shown in a frequency polygon
- the modal class is the group with the greatest frequency
- median cannot be found from grouped frequency tables
- calculate an estimated mean by adding the midpoints multiplied by the frequencies and dividing by the total frequency
- when there is a wide range of data with lots of values there are often too many entries for the frequency table
- histograms
- similar to a bar chart but continuous data only ( time or weight)
- the horizontal axis
- has the continuous scale and there are no gapes between the bars
- the area of each bar represents the frequency of the bar
- the height of the bar is called the frequency density
- frequency density= frequency class interval/ width of class interval
- the median is the value where the area of both is equal
- the lower quartile is the value that splits the area in the ratio 1:3
- the upper quartile is the value that splits the area in the ratio 3:1
- the data handling cycle
- outlining the problem and planning
- usually involves a hypothesis
- stating how the data will be collected
- saying how the data will be processed and represented
- usually involve working out means and measures of spread and showing the data in a suitable diagram
- interpreting the results and making a conclusion
- this should relate to the original hypothesis or problem
- outlining the problem and planning
- data and data collection
- qualitive
- this is data such as colour of cars
- discrete quantative
- this is numerical data that can only take certain values such as the number of people on a bus
- continuous quantative
- this is numerical data that can take any value in a range of values such as the weight of apples
- primary data
- this is data collected using surveys or experiments
- secondary data
- this is data collected from existing tables or lists
- look at historical data
- this would be used to predict whether it will rain on the 4th july in Edinburgh for example you would look back at records for all previous years
- experiment
- this would be used to test the probability of an event that cannot be predicted such as how many blue balls in a bag
- equally likely outcomes
- this is used when the probability of an event can be predicted for example taking a king from a pack of cards
- surveys
- this is used when there is no historical data and no way to predict probabilities a survey could be used to find what subject is the favourite amongst year 7 pupils
- qualitive
- averages and range
- when talking about the average its the same as the mean
- the lower quartile is the value that splits the area in the ratio 1:3
- there are four parts to the data handling cycle
- usually involve working out means and measures of spread and showing the data in a suitable diagram
- there are different types of data
- depending on what is being investigated there are four different ways to collect data
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