Stat1250_SGTA2 help

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1250

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Apr 3, 2024

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You are expected to read this material and think about the problems before coming to class. Participation in SGTAs is a hurdle requirement, you need to participate in at least 10 (see unit guide). SGTA 2: Statistical Studies In this SGTA we will: • Outline the SGTA programme. • Revise rounding and basic mathematical operations. • Discuss how to answer online quizzes. • Discuss populations, samples and study design. • Classify variables. • Collect data from you to understand who our students are and use this data for in our learning activities and/or assessments. SGTA Programme Aims SGTA work is based on topics introduced in the preceding week’s lecture. Attending the lecture or watching the recorded lecture prior to your SGTA will be beneficial to your learning. Without knowing what was learned in the lectures, you will struggle understanding and solving the problems in your SGTA. Our aim is to provide and active learning environment during SGTA classes. SGTAs are designed to improve students’ problem solving skills and develop critical thinking. They are designed to allow students to work in groups. Revision on rounding and basic mathematical operations 1. Round answers to the required number of decimal places ( dp ) as specified in the question. 1.49 rounds to 1.5(1dp) 1.49 rounds to 1(integer) 2. When rounding 5s, round to the next digit. For example, 1.65 should round to 1.7(1dp) 1.55 should round to 1.6(1dp) 3. These are the important signs to know: = When two values are equal, we use the "equals" sign Example: 3+2 = 5 < When one value is smaller than another, we use a "less than" sign Example: 3 < 15 Stat1250 SGTA2: Statistical Studies © Copyright Macquarie University 1

> When one value is bigger than another, we use a "greater than" sign Example: 3 > 1 To remember which way around the "<" and ">" signs go, a good technique is to remember that the “pointy end” of the operator always points to the small number. In other words: • Small < BIG • BIG > Small How to answer online quizzes 1. Round answers as shown above. 2. If the answer is less than 1 the 0 should be placed at the front. For example, .43 should be written as 0.43. 3. When calculating answers use calculator values which should be stored in memory instead of using rounded values. When using Excel for calculation, use the cell values, not rounded numbers until the last step. 4. If you are required to choose between 2 or more options do not include (). Exercise: Answer the following questions, using any relevant information shown above. Question Answer 1. Calculate the percentage of female students in your SGTA class (integer). 43 2. Round 106.53 to the nearest integer. 107 3. Round 1008.5 to the nearest integer. 1009 4. Round 1008.49 to the nearest integer. 1008 5. Round 97.5 to the nearest integer. 98 6. Calculate (15.563-13.185) (1 dp) 2.4 7. Calculate (15.563-13.185)/2 (2 dp) 1.19 8. Is this your first year at Macquarie University? (Y) Yes (N) No Y Populations, samples and study design As discussed in the lecture, the statistics helps us to make evidence-based decisions about a population (target population) based on evidence obtained from a sample. The target population contains all the units of interest and must be clearly defined. The sample is a manageable subset from the target population. Stat1250 SGTA2: Statistical Studies © Copyright Macquarie University 2

Only a representative sample should be used to make inferences about the target population. One way to ensure that a sample is representative of the target population is to obtain a random sample. A simple random sample is one where each member of the population has the same chance of being selected. 1. Discuss the following study with your group and answer the questions that follow. A group of Sydney researchers are trying to understand whether people aged 18-40 years are more likely to be tested positive to COVID -19 after attending anti-lockdown protests (see a relevant article at https://www.theguardian.com/australia-news/2021/jul/24/anti- lockdown protests-across-australia-as-covid-cases-surge-to-record-levels-in-sydney ). They are only interested in people living in Sydney. It is estimated that there were three thousand people at the anti-lockdown protest who were between the ages of 18 to 40 on 24 July 2021 event in Sydney. Individuals who were residents of Sydney within the age range will have the chance to be included in the sample for the study. The researchers will obtain health records to determine whether people were tested positive for COVID-19 within two weeks of attending the event and whether people had none, one or two doses of vaccine at that time as well as the type of vaccine (AstraZeneca, Pfizer/Biontec, Other). Please note the researchers were not considering 3 doses since at that time it was not possible to have 3 doses. Also, they will obtain police records (assuming each protester is recorded by police). Electoral role registration will provide a list of all Sydney residents. a. Is this an experimental study or an observational study? Give a reason for your answer. Observational – The researchers did not set up an experiment or engage with the members of the sample to obtain their results since the researchers are not allocating people to experimental and control groups. They are gathering data from different sources to allocate people to different groups but there is no intervention. b. What was the target population? Sydney residents between 18-40 who attended the protests ple living in Sydney aged 18- 40 c. Who needs to be in the sample? People in the age group of 18-40 People who were tested positive and negative People who had 1, 2 and 3 doses living in Sydney between the ages 18 to 40 whether they attended an antilockdown protest or not. Electoral role will be use. d. Identify the possible variables that needs to be recorded and specify their variable type. Variable Name Type Age Numerical, continuous Number of COVID vaccines Numerical, discrete Stat1250 SGTA2: Statistical Studies © Copyright Macquarie University 3

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Attendance at the protest Categorical, nominal (binary) Result of COVID test Categorical, nominal (binary) Gender Categorical, nominal (binary) Postcode Neither e. How would you obtain a representative sample to answer the researchers’ question? Put together a table of random numbers and allocate all Sydney residents between 18- 40 a number. Cluster sampling – taking a random sample from each postcode Stratified sampling Systematic 2. Suggest a method for selecting a representative sample of STAT1250 students. Put together a table of random numbers and allocate all STAT1250 students a number. Data Collection and Classification Each day the owner of a coffee shop located in the centre of a busy city records information about the following variables. Classify each of these variables. Variable Type Number of customers served: Stat1250 SGTA2: Statistical Studies © Copyright Macquarie University 4

1 = <50, 2 = 50 to <100, 3 = ≥ 100 Day’s revenue Number of short black coffees sold Quantity of full cream milk used Flavour of muffin available this day: 1 = chocolate, 2 = blueberry, 3 = orange We would like to learn about the students in STAT1250 Business Statistics. We have designed a survey and would like to collect anonymous data from you. Please follow this link ( https://forms.gle/Jyx6Ejy7v4pivMBb8 ) to answer the questions in the survey. Stat1250 SGTA2: Statistical Studies © Copyright Macquarie University 5

Stat1250_SGTA2 help

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