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Flashcards by Riya Patel, updated more than 1 year ago

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Edexcel Mathematics
A Level
Paper 2: Statistics and Mechanics

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Question | Answer |

Define 'measure of location' | A single value which describes a position in a data set |

Define 'measure of central tendency' | A single value that describes the centre of the data |

When is it suitable to use the mode? | When data is qualitative, or quantitative with either a single mode or two modes (bimodal) |

When is it suitable to use median? | For quantitative data and usually when there are extreme values as median is not affected by them |

When is it suitable to use the mean? | For quantitative data and as it uses all pieces of data, it gives a true measure of the data but is affected by extreme values |

What is the formula used for calculating the mean of data given in a frequency table? | ∑xf is the sum of the products of the data values and their frequencies ∑f is the sum of the frequencies Frequency Table Mean (binary/octet-stream) |

What do percentiles do to a data set? | Split it into 100 parts |

What is the formula used to find the lower quartile? | (n+1) / 4 |

What is the formula used to find the median? | (n+1) / 2 |

What is the formula used to find the upper quartile? | 3(n+1) / 4 |

Name the technique used to estimate the median, quartiles and percentiles when data is presented in grouped frequency tables | Interpolation |

What assumption is made when using interpolation? | That the data values are evenly distributed within each class |

What is the formula used for interpolation? | Interpolation (binary/octet-stream) |

Define 'variance' | How much each data point deviates from the mean by a certain amount |

What is Sxx and what is it's formula? | It is the sum of the squares Sxx (binary/octet-stream) |

What is the formula for variance? | Variance (binary/octet-stream) |

What are the units of variance? | The units of the data squared |

What is the formula for standard deviation? | It is the square root of the variance Standard Deviation (binary/octet-stream) |

What are the formulae for standard deviation and variance for grouped data that is presented in a frequency table? | Frequency Sd And Variance (binary/octet-stream) |

Define 'coding' | It is a way of simplifying statistical calculations and involves each data value being coded to make a new set of data values which are easier to work with |

What is the formula typically used to code data? | Where a and b are constants you have chosen or are given Coding (binary/octet-stream) |

If data is coded using the formula y=(x-a)/b, what is the mean of the coded data given by? | Coding Mean (binary/octet-stream) |

What is the standard deviation of the coded data given by? | Coding Sd (binary/octet-stream) |

Define 'outlier' | An extreme value that lies outside the overall pattern of the data Commonly defined as any value that is either greater than Q3 + k(Q3-Q1) or less than Q1 - k(Q3-Q1) |

Define 'anomalies' | These are outliers that should be removed from the data set since it is clear that is an error |

What is the process of removing anomalies from data known as? | Data cleaning |

What makes a data value an outlier? | If it is significantly higher or lower than the mean + standard deviation |

Name the diagram you can use to estimate the values of the median, quartiles and percentiles if you are given data in a grouped frequency table | Cumulative frequency diagram |

What type of data can be represented in a histogram? | Grouped continuous data |

In a histogram, what is the area of a bar proportional to? | The frequency in each class |

In a histogram, what does the height of each bar represent? | Frequency density |

What is the formula for frequency density? | Freq Density (binary/octet-stream) |

What does joining the middle of the top of each bar in a histogram form? | A frequency polygon |

When comparing data sets, what are the two things you can comment on? | A measure of location (median, mean, mode) A measure of spread (quartiles, variance, SD) |

Define 'bivariate data' | Data which has pairs of values for two variables (represented on scatter diagrams) |

Comment on the correlation Strong Ve (binary/octet-stream) | Strong negative correlation |

Comment on the correlation Weak Ve (binary/octet-stream) | Weak negative correlation |

Comment on the correlation No Correlation (binary/octet-stream) | No (zero) linear correlation |

Comment on the correlation Weak +Ve (binary/octet-stream) | Weak positive correlation |

Comment on the correlation Strong +Ve (binary/octet-stream) | Strong positive correlation |

What is a least squares regression line? | The straight line that minimises the sum of the squares of the distances of each data point from the line |

What are regression lines used for and what is this called? | To make predictions for values of the dependent variable that are within the range of the given data Interpolation |

What is the name of the method used to make predictions based on a value outside the range of the given data? | Extrapolation |

What is the main issue associated with using extrapolation to predict values? | It gives a much less reliable estimate |

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