IGCSEMathsEdexcelMaths BFlashcardsStatistics & ProbabilityStatistics Toolkit

Statistics Toolkit (Edexcel IGCSE Maths B): Flashcards

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  • FrontDiscrete & Continuous Data

    What is discrete data?

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  • What is discrete data?

    Discrete data refers to data that can only take certain numerical values. It is often (but not always) data that can be counted.

    Examples of discrete data include:

    • Number of pets

    • Shoe size

    • Number of petals on a flower

  • What is continuous data?

    Continuous data refers to data that can take any numerical value within a range. It is usually data that needs to be measured.

    Examples of continuous data include:

    • Height

    • Weight

    • Time taken to complete a jigsaw

  • How do you find the mean of a set of numbers?

    To find the mean of a set of numbers:

    1. Add the values together.

    2. Divide by the total number of values.

  • How do you find the median of a set of numbers?

    To find the median of a set of numbers:

    1. Put the numbers in order.

    2. Find the middle number.

    If there are two middle numbers then the median is the midpoint of those numbers.

  • How do you find the mode of a set of numbers?

    The mode of a set of numbers is the value that appears the most.

  • True or False?

    There can be more than one median value in a data set.

    False.

    There can not be more than one median value in a data set. The median is the middle value.

    The only average that can have more than one value is the mode.

  • True or false?

    The mean is affected by extreme values.

    True.

    The mean is affected by extreme values.

  • True or false?

    The median is affected by extreme values.

    False.

    The median is not affected by extreme values.

  • How can you find the total of all data values if you know the mean and the number of values?

    E.g. if the mean of a set of 25 values is 3.7, what is the total of all values in the data set?

    If you know the mean and number of values, you can calculate the total of values by rearranging the mean formula:

    • total space of space values equals mean space cross times space number space of space values

    E.g. if the mean of a set of 25 values is 3.7, then the total of all values in the data set is 3.7 cross times 25 equals 92.5.

  • How can you find the number of data values if you know the mean and the total of the values?

    E.g. if the total of a set of data values is 66 and the mean is 8.25, how many data values are there?

    If you know the mean and total of the data values, you can calculate the number of values by rearranging the mean formula:

    • number space of space values equals fraction numerator total space of space values over denominator mean end fraction

    E.g. the total number of data values in a set of data with a total of 66 and mean of 8.25 is fraction numerator 66 over denominator 8.25 end fraction equals 8.

  • How can you find the new mean of a data set if a new data item is added to the set?

    E.g. a data set of 12 items has a mean of 5.7.
    A new data item of 9.6 is added to the set.
    What is the new mean?

    To find the new mean of a data set if a new data item is added to the set:

    1. Find the total of the current data set: total space of space values equals mean space cross times space number space of space values

    2. Add the new data item

    3. Divide by the new total number of data items

    E.g. for a data set of 12 items and a mean of 5.7, the total of the values is 12 cross times 5.7 equals 68.4.
    Therefore when a new data item of 9.6 is added to the set, the new mean is fraction numerator 68.4 plus 9.6 over denominator 13 end fraction equals 6.

  • How do you find the mean from a frequency table?

    To find the mean from a frequency table:

    1. Include a column for (value cross times frequency).

    2. Add the values in this column.

    3. Divide the sum by the total frequency.

  • How do you find the median from a frequency table?

    To find the median from a frequency table:

    1. Make sure the values in the table are in order.

    2. Find the fraction numerator n plus 1 over denominator 2 end fractionth value, where n is the total frequency.

  • How do you find the mode from a frequency table?

    To find the mode from a frequency table, look for the value with the highest frequency.

  • A pie chart is drawn for a set of data where the total frequency is 180.

    What do you do to the frequency of each item to find its angle for the pie chart?

    If a pie chart is drawn for a set of data where the total frequency is 180, you multiply the frequency of an item by 2 (i.e. 360 ÷ 180) to find the size of its angle on the pie chart.

  • In a pie chart, if you know that the angle 30° represents a frequency of 10, how would you find the total frequency?

    In a pie chart, if an angle of 30° represents a frequency of 10, then you can find the total frequency by:

    • dividing 10 by 30 to find how much 1° represents,

    • then multiplying this by 360.

    Alternatively, you can see how many times 30° goes into 360° and then multiply this by 10.

  • How do you calculate the angles needed for a pie chart?

    To calculate the angles needed for a pie chart:

    • Divide each frequency by the total frequency.

    • Multiply each result by 360°.

    Alternatively:

    • Divide 360° by the total frequency.

    • Multiply each frequency by this number.

  • If you are given the angles in a pie chart and the total frequency, how do you calculate the individual frequencies?

    If you are given the angles in a pie chart and the total frequency, you can calculate the individual frequencies by doing the following:

    • Divide each angle by 360°.

    • Multiply by the total frequency.

    Alternatively:

    • Divide the total frequency by 360.

    • Multiply each angle by this number.

  • What sorts of things should you look for when reading and interpreting statistical diagrams?

    When reading and interpreting statistical diagrams, you should look for:

    • Keys

    • Shading

    • Axis labels

    • The word "frequency"

    • Any unusual or unexpected information mentioned

  • Define anomaly in the context of statistical diagrams.

    An anomaly, otherwise known as an extreme value or outlier, is a data point that is significantly different from the rest of the data.

  • True or false?

    You may be asked to comment on aspects of a statistical diagram that could be misleading or incorrect.

    True.

    You may be asked to comment on aspects of a statistical diagram that could be misleading or incorrect, such as uneven gaps in axis values or a missing key.

  • Define key in the context of statistical diagrams.

    In the context of statistical diagrams, a key is a legend that explains the meaning of symbols, colours, or shading used in the diagram.

  • True or False?

    The purpose of comparing statistical diagrams is to identify and comment on differences or similarities in averages, spread, and unusual data values for the data sets represented by the diagrams.

    True.

    The purpose of comparing statistical diagrams is to identify and comment on differences or similarities in averages, spread, and unusual data values for the data sets represented by the diagrams.

  • What should you consider when deciding which measures to compare in statistical diagrams?

    When deciding which measures to compare in statistical diagrams, you should consider:

    • Whether the mean, median or mode is the appropriate average to use.

    • Whether the range or interquartile range is the appropriate measure of spread to use.

    • Whether any assumptions or potential issues with the data could affect the reliability of the results and comparisons.

  • True or false?

    You should aim to make at least one pair of comments when comparing statistical diagrams.

    False.

    You should aim to make at least two pairs of comments when comparing statistical diagrams:

    • One pair should compare averages and comment on what this means in the context of the question.

    • The other pair should compare spread and comment on what this means in the context of the question.

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