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# Sample Size Estimation and Power Calculations with Excel

• 9:30am to 5pm
• 2 days

## Overview

This short course covers the basics of sample-size estimation, including both precision and power estimation approaches.

It's likely to be useful to those embarking on a research project, or trying to complete ethics and grant application forms.

You'll carry out practical workshop exercises using Excel sheets.

This course takes place in one day, 9.30am to 5pm.

This course is delivered by UCL's Centre for Applied Statistics Courses (CASC), part of the UCL Great Ormond Street Institute of Child Health (ICH).

## Course content

You'll be introduced to the concepts of sample-size estimation, including when and why this might be necessary.

Formulae are presented and discussed. You'll be given online access to a series of excel sheets which are pre-programmed to allow you to use the formulae.

In the first part of this course, the precision-based approach to estimating sample size is introduced, whereby the numbers are selected to produce a confidence interval for the relevant estimate with a specified width.

In the second part, we progress to the more traditional power calculations which aim to give the sample required to determine a specified difference with selected power and significance levels.

All terminology will be explained as it's introduced in the sessions.

Sample-size estimation is discussed for the following measurements:

• Means
• Proportions/ percentages
• Rates

Notes and spreadsheets are also provided to cover the following, which will be discussed if time permits:

• Time-to-event data
• Measures of agreement
• Percentiles

## Who this course is for

The course is open to anyone who wants to learn about the basics of estimating sample size.

Knowledge of the very basics of statistics (such as means, standard deviation, confidence intervals, etc.) is beneficial.

## Computers and software

You'll need to have Microsoft Excel (or alternative compatible software) installed on your computer.

## Learning outcomes

By the end of this course you should be able to:

• understand why sample-size calculation is important prior to starting a study
• recognise and understand the two different types of sample-size estimation - precision and power
• understand the components required for sample-size calculation and how to estimate these
• undertake sample-size calculation using the online excel sheets
• adjust for unbalanced sample sizes in two groups
• recognise and appropriately adjust for non-independent outcome measures

## Cost and concessions

The fees are as follows:

• External delegates (non UCL) - £175
• UCL staff, students, alumni - £87.50*
• ICH/GOSH staff and doctoral students - free

* valid UCL email address and/or UCL alumni number required upon registration

## Certificates

You can request a certificate of attendance for this course once you've completed it. Please send your request to ich.statscou@ucl.ac.uk

Include the following in your email:

• the name of the completed course for which you'd like a certificate
• how you'd like your name presented on the certificate (if the name/format differs from the details you gave during registration)

## Cancellations

Read the cancellation policy for this course on the ICH website. Please send all cancellation requests directly to the course administrator.

## Find out about other statistics courses

CASC's stats courses are for anyone requiring an understanding of research methodology and statistical analyses. The courses will allow non-statisticians to interpret published research and/or undertake their own research studies.

Find out more about CASC's full range of statistics courses, and the continuing statistics training scheme (book six one-day courses and get a seventh free.)

## Course team

### Dr Eirini Koutoumanou

Eirini has a BSc in Statistics from Athens University of Economics and Business and an MSc in Statistics from Lancaster University (funded by the Engineering and Physical Sciences Research Council). She joined UCL GOS Institute of Child Health in 2008 to develop a range of short courses for anyone interested in learning new statistical skills. Soon after, CASC was born. In 2014, she was promoted to Senior Teaching Fellow. In 2019, she successfully passed her PhD viva on the topic of Copula models and their application within paediatric data. Since early 2020 she has been co-directing CASC with its founder, Emeritus Professor Angie Wade, and has been the sole Director of CASC since January 2022. Eirini was promoted to Associate Professor (Teaching) with effect from October 2022.

### Dr Chibueze Ogbonnaya

Since joining the teaching team at CASC in February 2019, Chibueze has contributed to the teaching and development of short courses. He currently leads and co-leads short courses on MATLAB, missing data, regression analysis and survival analysis. Chibueze has a BSc in Statistics from the University of Nigeria, where he briefly worked as a teaching assistant after graduation. He then moved to the University of Nottingham for his MSc and PhD in Statistics. His research interests include functional data analysis, applied machine learning and distribution theory.

Learner reviews

"Very well-run courses at an affordable price."

"The teacher was excellent!"

"Very interesting and informative. Materials distributed remain highly useful."

"Very good course, definitely useful and [the] spreadsheets provided are very handy."