GCSE Statistics Keywords Verified Answer

GCSE Statistics Keywords Verified Answers Bivariate data ️️Data that involve two variables Data ️️Information that has been collected Discrete data ️️Data that can only take certain numerical values in a given range, e.g. Shoe sizes Hypothesis ️️An assumption made as the starting point of an investigation. It should be a statement. Qualitative data ️️Observations that do not have numerical values and must be described in words, e.g. Colour Quantitative data ️️Observations that can take numerical values; that can be measured and given as a number Variable ️️A quantity that can have different values Continuous data ️️Data that can take any value on a continuous scale, e.g. time; usually rounded Census ️️Information about every member of the population Population ️️Everybody or everything that could be involved in the investigation, e.g. Members of a school Random sample ️️The sample in which the people or items are chosen without making a conscious decision. Each person or item has an equal chance of being selected Sample data ️️Information about part of the population Sampling frame ️️A list of all the people or items in the population, e.g. a register of members of the school Sampling units ️️All the people or things in the population Advantages of a census ️️Unbiased Takes the whole population into account - Accurate Disadvantages of a sample ️️May be biased Not completely representative Disadvantages of a census ️️Expensive Time consuming Lots of data to handle - Difficult to ensure the whole population is being used Advantages of a sample ️️Cheaper Less time consuming Easy to manage Simple random sampling ️️1) Number each item on the sampling frame 2) Obtain the required number of random numbers from a generator, table etc. 3) Select the items with these numbers Stratified sampling ️️A sample when a population can be divided into strata (sub-populations), each represented fairly, with items randomly selected within each stratum. Cluster sampling ️️Clusters are natural groups. A sample of the clusters is selected randomly and observations are taken from each member of these groups. Quota sampling ️️Pre-specified numbers of the population are taken with certain combinations of characteristics, e.g. Sex, age etc. Systematic sampling ️️Every nth person or unit on an unordered list is selected, beginning at a random point Simple random advantages ️️Simple and cheap Simple random disadvantages ️️Not suitable for large populations A sampling frame is needed Stratified sampling advantages ️️More accurate when clear strata present Stratified sampling disadvantages ️️Overlap may occur between strata Same disadvantages in each stratum as simple random sampling Cluster sampling advantages ️️Cheaper Suitable for large populations Cluster sampling disadvantages ️️Less precise other methods Clusters must be uniformly made Quota sampling advantages ️️Fieldwork can be done quickly in a small sample size Quota sampling disadvantages ️️Not a random process Interviewer must judge characteristics Interviewer can introduce bias Systematic sampling advantages ️️Simple to use Suitable for large samples Systematic sampling disadvantages ️️Sampling frame should be random It can introduce bias Closed question ️️A question that has a set of answers to choose from Leading question ️️A question that leads the respondent to an answer Open question ️️A question that gives no suggested answers Pilot survey ️️A small scale replica of a survey done to find out if the main survey will work Primary data ️️Data collected by or for yourself e.g. Heights in your class Secondary data ️️Data collected by someone else for their own use, e.g. From websites Primary data advantages ️️You know how data were obtained You know the accuracy of the data Secondary data disadvantages ️️Method of collection unknown