How-To Guide: Selecting Mobile Devices

December 13, 2011

You approach to selecting the device for your mobile project will depend on whether you’re doing a technology refresh or working on a brand new deployment. For phase II projects, you will usually have a good enough understanding of what worked and what didn’t in your current solution — and will choose the device accordingly. For brand new mobile initiatives, the task may prove more difficult. At Syclo, we use a three step weighted average process for evaluating devices for each application and user group:

1) Design your weighing criteria: understand which device attributes are important to you

2) Assign a weight to each criterion: define the relative importance of each attribute

3) Evaluate each potential device, ranking it across the above attributes and computing the weighted average score for the device.

Step 1

In the first step, you need to define a set of characteristics that are important to you and your users. Some of the criteria our customers have used in the past include:

Criteria	Explanation
Device size	This can range from full-sized laptops to small handheld devices.
Device weight	This is an important criterion, since it defines how portable the device is outside of a vehicle. For applications that involve a lot of physical movement or holding the device up to enter data, excessively heavy devices will put undue strain on your users.
Handing options	How the device is held. For scan-intensive environments, a pistol-grip device is preferred to a palmtop or a tablet device. For many hands-on work processes (like some of the inventory operations), hands-free operation may be a good option to consider.
Screen size and resolution	The screen size you choose depends on the amount of data or graphical content you want your users to see at once. Although even complex forms and application screens can be broken down into several steps for use on smaller devices, some content like GIS or detailed schematics may be too hard to interact with on smaller screens.
Screen brightness	Determine if the device will be used in high ambient lighting conditions or in direct sunlight. Most consumer-grade devices aren’t bright enough to make prolonged outdoor use comfortable.
Hardware keyboard	The presence and size of the hardware keyboard can impact the device’s usability and user productivity in environments where heavy alpha-numeric entry us required.
Connectivity options	Although you probably won’t find a device without at least a Wi-Fi radio built in, understand your needs for WLAN connectivity and speed. Depending on the application and your user base, a 3G, 4G or even a satellite connection may be required.
Speed of processor	Understand how complex and resource-intensive your application is and choose your device accordingly. Although smaller handheld devices have become much more powerful, applications that perform advanced business logic, manipulate large data sets or render detailed graphical content on the device may be best deployed on faster laptop and tablet PC hardware.
Peripheral support	Peripherals like barcode scanning, RFID, NFC, digital cameras and others can play an important role in increasing application usability and user productivity. We’ll touch on common peripherals later in this paper.
Storage capability	This refers to the amount of data you can store and operate with locally on the device. A well-designed mobile application can be very frugal in its device footprint, but solutions that require large data sets (such as customer lists with associated documentation or complex job plans) can eliminate quite a few devices from your roster of possibilities.
Battery capacity and charging time	Understand what your needs and usage patterns are. If the device needs to handle a full shift of work, then it needs to come with a large enough battery (or at least an interchangeable battery). If the device needs to be used by an incoming shift right after, then it needs to charge quickly.
Operating system	Although designing your solution around a single OS may not always be a viable option, understand which operating system you’d prefer for the majority of your users. This will define what devices you can choose and how complex an application you’re able to run on the device.
Resistance to temperature	From sitting in direct sunlight at a job site to getting cold soaked in the truck overnight , mobile devices can go through a lot. Devices unprepared to handle this (with special cases, heated hard drives, etc.) will go through frequent replacement and will end up degrading the ROI of your mobile project.
Ruggedness	The same logic applies to how much abuse you expect your devices to take. Using consumer-grade devices in demanding environments (frequent drops, dust, hundreds of on-screen signatures a day) will prove to be more expensive than specifying a more durable device from the start.
Intrinsic safety	This is more of an inclusion/exclusion criteria. Intrinsic safety is the device’s ability to operate in hazardous areas (e.g. oil platforms) without a possibility of causing a spark and igniting flammable substances in the air.
Price	Price is obviously a consideration, but you need look at it as part of your total cost of ownership over a certain time period. Devices that can take a beating or devices that can be upgraded to handle your future peripheral needs may prove to be a more cost-effective option even if they cost more upfront.

The above obviously isn’t a comprehensive list of criteria, and other device characteristics may matter more for your project. Our advice is to evaluate devices across five to seven meaningful dimensions to keep the process manageable.

Step 2

The second step involves assigning weights to the criteria you have selected. To do this, think about the importance of each criteria on a 1-100 scale, keeping in mind that the sum of all the weights has to equal 100. For example:

This will force you to think about how important the different attributes are relative to each other, making real-world device differences more meaningful.

Step 3

In the third step, rate each device you’re considering on a 1-10 scale across the criteria you have defined, and compute the weighted average scores. The result will look something like this:

There will probably be subjective factors that will impact your decision (customer references, your experience and relationship with the manufacturer, etc.), but the weighted average score framework is the closest you can get to objectively evaluating the differences among devices and their impact on your project.

Even if you’re completely happy with the device you have selected for your initial deployment, avoid hard-coding your mobile application for that specific device model. When it is no longer available (which WILL happen in the lifetime of your solution), it can be very costly to modify such hard-coded applications. When possible, choose a software vendor or a development approach that can account for future changes in the device landscape with only minor app modifications.

jgranda's blog

How-To Guide: Selecting Mobile Devices

Comments

Post a comment

Featured Content

Filter Posts by Topic

Subscribe to our Blog