sadc course in statistics session 4 & 5 producing good tables

SADC Course in Statistics

Session 4 & 5

Producing Good Tables

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Learning Objectives

students should be able to • Explain the properties of a table

• and their role in the data analysis process

• Produce a frequency table • by hand and using Excel Pivot Tables

• Produce a table • with counts, proportions & percentages

• Improve a table• Hide, re-order and merge categories in a table

• Display tables • with an appropriate format, • and with or without the margins


Contents

• Examples of one-way tables

• Why do we need tables

• Practical 1 – • CAST for one-way tables• Tables “by hand”• tables of counts, proportions and percentages

• Discussion

• Practical 2• Pivot tables in Excel

• Discussion


Example 1 – a one-way table

Sources of drinking water for households in rural Tanzania in 2002/3

Two summary statistics

Counts and percentages

Table margin (gives totals)


Example 2 - also a one way table

TB cases in SADC countries in 2005

Three summary statistics


Example 3 – Responses to survey

Response rates for UN survey on the principles of official statistics

Twelve summary statistics! (Not six?)


Example 4 – the principles adopted?

Nine one-way tables – still in Excel

Percentages Counts

How could you deduce the individual counts?


Same information – in a graph

Tables first – later sessions look at graphs


A 2-way table

Two-way because 2 factor (categorical) variables

Type of country (3 levels) and Principle 4 (4 levels)

The table margins of a two-way tableare one-way tables

In this course we mainly cover one-way tables


Why do we need tables?

• Data checking and data cleaning

• To capture the information in the data and summarize it in different ways

• Reference tables in appendices

• Presentation of results


Types of tables

• One-way Tables–How often does a particular variable’s category occur?

• Two-way tables (or higher)–What is the relationship between two (or more) categorical variables?–How often does a particular variable occur at each combination of category levels

Type of table depends on type of data & the question being answered We concentrate here largely on 1 way tables


A one-way table..

• Frequency tables can be made using– tallies ( by hand or with computer)– using the pivot table facility in Excel

• Frequency table can be made to – show counts – actual frequencies– Proportions – relative frequencies– Percentages- proportions multiplied by 100;

easier to compare


A one-way table

• As an exploratory tool, can be used to– give overall frequency distribution – reveal incorrect categories– reveal categories with few observations

• As a presentation tool, can be used to– summarize results and interpret the findings so

that it highlights the key features of the data


Formatting

• Suitable formatting and displaying can make a lot of difference to the ‘readability’ of the table, one should consider:– Number of decimal places– Spacing– Alignment– Ordering of categories– Merging of groups– Labelling of groups– etc


Practical 1

• Use CAST to learn more about tables

• A simple way to get a frequency table • is to tally the numbers in each category by hand • enter the summary data into Excel • and work out the proportions and percentages• from the frequencies

• These are activities 2 to 5


Discussion of Practical 1 – activity 2

• This layout is the “usual one

• That’s because surveys have a lot of questions

• Here you can process each variable in turn


Activities 3 and 4

• Was the demonstration useful?

• What points were new to you, if any?

• Report on your results at the end of activity 4

• a – this is a frequency or count• b – this percentage is just 100 – 22.7 = 77.3 • c – this is just the percentage divided by 100• d – this is a “conditional” question.• The answer is 100*(13.6/(13.6+27.2))=33% or 1/3


Activity 5• What did you reply for your country on

principle 1?

• What were your responses on• a• b• c – not possible with a 1-way table – 2-way table below• d – not possible with a 1-way table – 2 way table below


Tables from the raw data

• So far you have tallied “by hand”• To get the counts or frequencies

• And then used Excel • to get proportions and percentages

• Now you start with the raw data

• And use Excel’s pivot-tables

• To do the whole process

• There is a demonstration to start you off


Practical 2• The usual way of making tables with Excel

• Uses the pivot-table wizard

• This is explained in the demonstration “Using Pivot Tables”.

• First watch the demonstration• That is Activity 5

• Then practice the skills• with a second data set• These are Activities 6 to 8


How easy were these tasks?

No

Task How easy?

Comment

1 Order of categories

2 Name of category

3 Percentage instead

4 Format data

5 Frequency and percentage

6 Hide a field

7 Interpret a percentage

8 Hide a margin

9 Merge levels


Summary

• One-way tables are a useful tool • for presenting summaries on the categories of a single

variable.

• Tables can be made by hand

• or by using special software facilities

• e.g. Pivot table Wizard in Excel

• Appropriate formatting and display is used• to present the summary effectively


The next 2 sessions are similar to these, but on how to produce good graphs (charts)

sadc course in statistics session 4 & 5 producing good tables

Documents

view header

oneway tables tables

table display tables

frequency tables

data slide

types of tables oneway

tables practical

twoway tables