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Statistics
Cards for revision
Term | Definition |
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Primary Data | Data that you collect yourself or is is collected by somewhere under your direct supervision. |
Secondary Data | Data that has already been collected and made available from an external source. |
Univariate Data | When one piece of data is collected from each member of the sample. |
Bivariate Data | When two pieces of data are collected from each member of the sample. |
Quantitative Data | Data that is counted or measured. |
Discrete Data | Data that can only take particular values. |
Continuous Data | Data that can take any value within a range. |
Qualitative Data | Data that cannot be measured. |
Categorical Data | Data that can only be described in words and are organised into categories. |
Ordinal Data | Data that are organised in logical order or ranking. |
Population | Complete set of data under consideration. |
Census | A collection of data relating to a population. |
Sampling Frame | List of every item in a population. |
Sample | Small part of the population selected. |
Random Sample | A sample in which every member of the population has an equal chance of being collected. |
Statistical Inference | Conclusions drawn from a sample that are applied to the whole population. |
Bias | Anything that distorts data so that they will not give a representative sample. |
Sample Survey | A survey that collects data from a sample of the population, usually using a questionnaire. |
Experiment | A controlled study in which the researcher understands the cause-and-effect relationships. |
Observational Studies | Data obtained by making observations are called observational studies. |
Designed Experiments | Data obtained from an experiment by counting or measuring. |
Questionnaire | A set of questions used to obtain data from a population |
Respondent | Anyone who answers a questionnaire. |
Measures of Centrality | Mean, Median and Mode. |
Mean | The sum of all the values of a data set divided by the number of values in the set. |
Mode | The item that occurs most in a set of data. |
Median | The middle value in a set of data. |
Measures of Variability | Range, Standard Deviation and Interquartile Range. |
Range | highest value - lowest value. |
Standard Deviation | A measure of deviation from the mean. |
Interquartile Range | Measure of the values that lie in the 2nd and 3rd quartiles. |
Histogram | Visual Representation used to represent discrete or continuous data. |
Back-to-back Stem and Leaf Diagrams | Used to compare two samples by showing the results together on a back-to-back stemplot. |
Scatter Diagram | Visual Representation used to display the relationship between two variables. |
Correlation | Used to imply a connection between variables. |
Line of best fit | A visual representation between a scatter and a trend line. |