# SADC Course in Statistics Objectives and analysis Module B2, Session 14.

## Presentation on theme: "SADC Course in Statistics Objectives and analysis Module B2, Session 14."— Presentation transcript:

SADC Course in Statistics Objectives and analysis Module B2, Session 14

To put your footer here go to View > Header and Footer 2 Learning Objectives students should be able to Explain some criteria for modifying initial objectives, once the data are available Explain the importance of specifying objectives precisely before starting an analysis Be able to outline a simple table or graph that corresponds to a stated objective Be able to complete a simple table or graph given an objective and an outline. Review a table or graph to specify to what objective(s) this presentation corresponds

To put your footer here go to View > Header and Footer 3 Contents Introduction of the ideas Sitting in on a review class (Flash presentation) Practical work Using rice survey and the Tanzania survey Discussion

To put your footer here go to View > Header and Footer 4 Defining the objectives of the study In defining statistics (Session 3) Statistics is NOT just collecting numbers It is collecting numbers with a purpose So, as part of the planning for a study You must specify the objectives You need this also, before getting a budget! Once you have your overall objectives You plan the study Collect the data And get the data ready for analysis

To put your footer here go to View > Header and Footer 5 Analysis objectives Before you start the analysis You review the overall objectives Possibly modify them for the analysis Why? 1.Perhaps some objectives are not possible Questions may have been misunderstood Questions answered in an inappropriate manner etc 2.Perhaps new objectives become possible A practical complication adds a new objective A minor point becomes more crucial

To put your footer here go to View > Header and Footer 6 Overall objectives – small example Rice survey Two objectives 1.Estimate total rice production in the district 2.Investigate the possible relationships between production and cultural practices and justify the questions in the study

To put your footer here go to View > Header and Footer 7 The district for the rice survey

To put your footer here go to View > Header and Footer 8 The data ready for analysis

To put your footer here go to View > Header and Footer 9 Objectives and measurements The objectives led to the questions the measurements we took 1st objective – total yield in the district So we measured the yield on sampled plots 2 nd objective – relationships with cultural practice so we asked about size of field, fertilizer, variety See how the objectives lead directly to the questions

To put your footer here go to View > Header and Footer 10 Objectives of the analysis Now the data are ready for analysis Can we still meet the objectives? Possibly – so continue with both parts to the analysis But suppose we now realised that date of planting was crucial, and not measured or there was disease on some fields, not recorded Perhaps the 2 nd objective is not attainable So look carefully at the objectives And be prepared to rewrite them Or state them more precisely

To put your footer here go to View > Header and Footer 11 Breaking the curse of variation! Statistics is concerned with studies where variation is important Otherwise you only need a sample of size 1! This was discussed in the Concepts Session - Session 3 Hence also take measurements if they may help to explain variation in the data even if that measurement is not related to a specific objective Understanding variation in key variables like the yield in this rice survey Is effectively an objective itself in all statistical studies Then the analysis can adjust for these aspects

To put your footer here go to View > Header and Footer 12 Objectives once you see the data Sometimes looking at the variables permits you to specify objectives Thats not as good as starting with them But it is still useful And the tables and graphs Should then follow directly From the objectives of the analysis This is illustrated in the demonstration Look for the following 2 slides in particular

To put your footer here go to View > Header and Footer 13

To put your footer here go to View > Header and Footer 14 Tables and graphs to satisfy objectives

To put your footer here go to View > Header and Footer 15 Practical work Do practical 1 It benefits from discussion So it is good for students to work in pairs First is an demonstration lesson This should partly be revision Complete the sections in the practical sheet as watch the lesson Then the rice survey data are analysed Finally data from the Tanzania agriculture survey are processed

To put your footer here go to View > Header and Footer 16 The Tanzania agriculture survey Here is a second example From the Tanzania agriculture survey Page 2 of their technical guide The details are less important, than that the objectives are stated carefully and justify the questions in the study questionnaire

To put your footer here go to View > Header and Footer 17 Overall statement: Sample census objectives The 2003 Agriculture Sample Census was designed to meet the data needs of a wide range of users down to district level including policy makers at local, regional and national levels, rural development agencies, funding institutions, researchers, NGOs, farmer organisations, etc. As a result the dataset is both more numerous in its sample and detailed in its scope compared to previous censuses and surveys. To date this is the most detailed Agricultural Census carried out in Africa

To put your footer here go to View > Header and Footer 18 The sample census was carried out to: Identify structural changes if any, in the size of farm household holdings, crop and livestock production, farm input and implement use. Determine if there are any improvements in rural infrastructure and the level of agriculture household living conditions; Provide benchmark data on production and agricultural practices in relation to policies and interventions promoted by the Min. of Agriculture and Food Security and others stake holders. Establish baseline data for the measurement of the impact of high level objectives of the Agriculture Sector Devt Programme (ASDP), National Strategy for Growth and Reduction of Poverty (NSGRP) and other rural development programs and projects. Obtain benchmark data to address specific issues, such as: food security, rural poverty, gender, agro-processing, marketing, service delivery, etc.

To put your footer here go to View > Header and Footer 19 Analysis to meet objectives Overall reports have been produced In addition, the data can be used for a wide range of objectives The practical assumes 2 NGOs with particular questions One is on food security The other is on energy for lighting

To put your footer here go to View > Header and Footer 20 Food security Why is a pie chart a reasonable type of display?

To put your footer here go to View > Header and Footer 21 Food security by district Why might a stacked bar chart be appropriate?

To put your footer here go to View > Header and Footer 22 Energy use for lighting Required 1. Decreasing order 2. With small categories combined

To put your footer here go to View > Header and Footer 23 Tables sorted and then grouped

To put your footer here go to View > Header and Footer 24 Horizontal bar chart – for long titles

To put your footer here go to View > Header and Footer 25 Finally: Are you now able to Provide some principles that characterise good tables and graphs Use these principles to recognise examples of good practice Suggest reasoned improvements for tables and charts Provide examples of improved presentations Be able to extract points from a table or graph for a talk or a report

To put your footer here go to View > Header and Footer 26 In the next session these ideas are applied to numeric variables