[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"doc-detail-208335-en":3,"doc-seo-208335-105":30,"detail-sidebar-cat-0-en-105":90},{"code":4,"msg":5,"data":6},0,"success",{"doc_id":7,"user_id":8,"nickname":9,"user_avatar":10,"doc_module":4,"category_id":11,"category_name":12,"doc_title":13,"doc_description":14,"doc_content":15,"file_id":16,"file_url":17,"file_type":18,"file_size":19,"view_count":4,"is_deleted":4,"is_public":20,"is_downloadable":20,"audit_status":20,"page_count":21,"language":22,"language_code":23,"site_id":24,"html_lang":23,"table_of_contents":25,"faqs":26,"seo_title":27,"seo_description":14,"update_tm":28,"read_time":29},208335,2336477552062,"Stanford","https://ap-avatar.wpscdn.com/davatar_994ba38a5ba835b3df7d355c54d3ed8d",4,"Exam","GCSE Statistics Revision Notes - Key Methods, Data Types and Calculations","GCSE Statistics revision notes covering core topics from collecting data to interpreting results. The material explains sampling methods such as random, stratified, systematic, cluster, quota and convenience sampling, plus census. It compares primary vs secondary data, quantitative vs qualitative, continuous vs discrete, and details questionnaires including open and closed questions and pilot surveys. Further sections address mean, standard deviation, variance, standardised scores, normal distribution, scatter diagrams, causal relationships, Spearman’s rank correlation and index numbers with practical examples.","GCSE Statistics Revision notes  \nCollecting data  \nSample – This is when data is collected from part of the population. There are different methods: Random sampling, Stratified sampling, Systematic sampling, cluster sampling, Quota sampling, Convenience sampling  \nRandom sample – Where each piece of data has an equal chance of being picked.  \nMethods  \nRandom number table – Tables of random numbers can be used.  \nHere is an extract from a table of random numbers  \n36015 37672 90153 67480 26237 10635 34269 01638 Split the numbers into to digit numbers  \n36 01 53 76 72 90 15 36 74 80 26 23 71 06 35 34 26 90 16 38 And then start from 36 and select numbers between 0 and 50  \n36 01 15 36 26 Leave out any numbers above 50 (in this case) Calculator – Use the RAN button on your calculator. For numbers from 0 to 100 type  \n100 Shift RAN Until you have enough numbers. Numbers in a bag, internet random number generator etc  \nStratified sample – Where the data sampled is in proportion to the population. Example: The table shows the number of students in a school  \nYear Students  \n7 120 8 100 9 115  \n10 125  \nTotal 460  \nA stratified sample of size 30 is to be taken. How many year 7s will be picked? Solution: Fraction of year 7 students in school is  120  \n240  \n120 x 30 = 7.82… so approx 8 year 7 students will be picked  \n240  \nOther Sample techniques  \nConvenience sample – the first so many pieces of data in the list are sampled.  \n(Quick but unlikely to be representative. )  \nQuota sample – The amount or quota of each group is given eg 100 woman were sampled Systematic sampling – Data is chosen at regular intervals eg Every 10th Person.  \nCluster sampling – The population is divided into groups (cluster) and then a group is chosen at random.  \nCensus – This is when all of the data in the population is taken. For example a census of the entire  \npopulation of the UK is taken every 10 years.  \n\n|  | Advantage | Disadvantage |\n| --- | --- | --- |\n| Sample | Cheaper | Not completely representative |\n|  | Less time consuming | Possibly biased |\n|  | Less data to be analysed |  |\n| Census | Unbiased | Time consuming |\n|  | Accurate | Expensive |\n|  | Takes account of whole population | Difficult to ensure whole population is used. |\n\nTypes of Data  \nPrimary data-This is data collected by the person doing the analysis  \nAdvantage-Should be reliable.  \nDisadvantage – Collecting is time consuming.  \nSecondary data – This is data that has been collected by someone else.  \nAdvantage-No need to collect. Ready to analyse.  \nDisadvantage – Could be unreliable  \nQuantitative data – This is data that has numerical values. (Time, heights, weights, number of people)  \nQualitative data-This is data that is not numerical (Colour, type)  \nContinuous Data – This is data that is on a continuous scale (Lengths, height, weights, measurements) Discrete Data-This data that consists of separate numbers. (Shoe sizes, number of people, money)  \nQuestionnaires  \nOpen questions – Has no suggested answers and gives people chance to reply as they wish  \nAdvantage –Allows for a range of answers  \nDisadvantage – Range of response too broad-hard to analyse Closed questions – Gives a set of answer for the person to choose from  \nAdvantage – Restricts response making it easy to analyse responses  \nDisadvantage – Will not necessarily cover all responses  \nPilot survey (pre-test)– Small scale replica of the survey to be carried out. Used to ensure that the method of Data collection / questionnaire and data required is suitable for the bigger survey.  \nLeading question – Avoid questions that infer an opinion such as “Smoking is bad for you”,“Do you agree?”  \nCalculations  \nMean from frequency table  \nExample  \nMean from grouped data  \nFind the mid-point of each group and then multiply by frequency. Sum and then divide by total frequency Example  \nStandard Deviation  \nVariance is a measure of spread about the mean of a distribution of data. The square root of the variance is the","cbCaihxmADNiqfiZ","https://ap.wps.com/l/cbCaihxmADNiqfiZ","pdf",709609,1,10,"English","en",105,"# Collecting data\n## Sampling methods\n## Census\n# Types of data\n## Primary and secondary data\n## Quantitative and qualitative data\n## Continuous and discrete data\n# Questionnaires\n## Open vs closed questions\n## Pilot survey\n# Calculations\n## Mean from frequency and grouped data\n## Standard deviation and variance\n## Standardised scores\n## Normal distribution\n## Scatter diagrams and line of best fit\n## Causal relationships\n## Spearman’s rank correlation\n## Index numbers\n## Chain base index numbers\n# Weighted means","[{\"question\":\"What is the difference between random sampling and stratified sampling?\",\"answer\":\"Random sampling gives each data item an equal chance of being selected. Stratified sampling takes data in proportion to the population, such as selecting students from each year group based on their counts.\"},{\"question\":\"How do you find the mean for grouped data?\",\"answer\":\"Find the midpoint of each group, multiply each midpoint by its frequency, sum the results, then divide by the total frequency.\"},{\"question\":\"What is standard deviation and how is it related to variance?\",\"answer\":\"Variance measures the spread of data about the mean. Standard deviation is the square root of the variance.\"}]","GCSE Statistics Revision Notes - Key Methods, Data Types and Calculations | PDF",1788603528,25,{"code":4,"msg":31,"data":32},"ok",{"site_id":24,"language":23,"slug":33,"title":13,"keywords":34,"description":14,"schema_data":35,"social_meta":85,"head_meta":87,"extra_data":89,"updated_unix":28},"gcse-statistics-revision-notes-key-methods-data-types-and-calculations","",{"@graph":36,"@context":84},[37,53,67],{"@type":38,"itemListElement":39},"BreadcrumbList",[40,44,48,51],{"item":41,"name":42,"@type":43,"position":20},"https://docshare.wps.com","Home","ListItem",{"item":45,"name":46,"@type":43,"position":47},"https://docshare.wps.com/document/","Document",2,{"item":49,"name":12,"@type":43,"position":50},"https://docshare.wps.com/document/exam/",3,{"item":52,"name":13,"@type":43,"position":11},"https://docshare.wps.com/document/gcse-statistics-revision-notes-key-methods-data-types-and-calculations/208335/",{"url":52,"name":13,"@type":54,"author":55,"headline":13,"publisher":57,"fileFormat":60,"inLanguage":23,"description":14,"dateModified":61,"datePublished":61,"encodingFormat":60,"isAccessibleForFree":62,"interactionStatistic":63},"DigitalDocument",{"name":9,"@type":56},"Person",{"url":41,"name":58,"@type":59},"DocShare","Organization","application/pdf","2026-09-05",true,{"@type":64,"interactionType":65,"userInteractionCount":4},"InteractionCounter",{"@type":66},"ViewAction",{"@type":68,"mainEntity":69},"FAQPage",[70,76,80],{"name":71,"@type":72,"acceptedAnswer":73},"What is the difference between random sampling and stratified sampling?","Question",{"text":74,"@type":75},"Random sampling gives each data item an equal chance of being selected. Stratified sampling takes data in proportion to the population, such as selecting students from each year group based on their counts.","Answer",{"name":77,"@type":72,"acceptedAnswer":78},"How do you find the mean for grouped data?",{"text":79,"@type":75},"Find the midpoint of each group, multiply each midpoint by its frequency, sum the results, then divide by the total frequency.",{"name":81,"@type":72,"acceptedAnswer":82},"What is standard deviation and how is it related to variance?",{"text":83,"@type":75},"Variance measures the spread of data about the mean. 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