Maths and Stats

• Bar chart


  A graph used to represent the frequencies of nominal (category) or discrete (discontinuous) data.
• Coding


  The process of placing quantitative or qualitative data in categories.
• Descriptive statistics

  A way of summarising a data set using measures of central tendency and dispersion.
• Fraction, percentage, decimal, ratio


  Methods of expressing parts of a whole.
• Histogram


  A graph showing the frequency distribution of continuous data.
• Inferential statistics


  Statistical tests to find out the likelihood that a result could have occurred simply by chance in a sample.
• Level of significance

  The level of error we are prepared to accept, for example p<0.05 means there is less than 5% chance that the difference or association occurred by chance in a sample.
• Mean


  The arithmetic average of a data set.
• Measure of central tendency


  A descriptive statistic that provides information about a ‘typical’ value in a data set.
• Measure of dispersion


  A descriptive statistic that provides information about how spread out the data are in a data set.
• Median


  The middle value of a data set when the items are placed in rank order.
• Mode


  The most frequently occurring value or category in a data set.
• Negatively skewed distribution


  Most of the scores are bunched to the right. The mean is affected by extreme scores in the long tail to the left, so the mean is to the left of the mode.
• Normal distribution


  A symmetrical bell-shaped frequency distribution curve. The mean, median and mode are at the mid-point.
• Positively skewed distribution


  Most of the scores are bunched to the left. The mean is to the right of the mode because it is affected by the long tail on the right.
• Range


  The difference between the highest and lowest item in a data set. Usually 1 is added as a correction.
• Sign test

  An inferential statistical test to determine the significance of a difference in scores in a sample of related items.
• Significance


  A statistical term indicating that the association between variables is sufficiently strong for us to accept the research hypothesis under test.
• Significance


  A statistical term indicating that the research findings are sufficiently strong to enable a researcher to reject the null hypothesis under test and accept the research hypothesis.
• Skewed distribution


  A frequency distribution in which the scores are not evenly distributed either side of the median.
• Standard deviation

  The spread of data around the mean.
• Type I error


  Occurs when a researcher rejects a null hypothesis that is true.
• Type II error


  Occurs when a researcher accepts a null hypothesis that was not true.