How to use and customize the app.
The EstimationLine instructions contain information on how to access the collected data as well as configure the app.
The EstimationLine instructions contain information on how to access the collected data as well as configure the app.
The EstimationLine app is a proven estimation test for children to show where a target number should fall on a number line. In this iPad app, children touch the line with their finger to position their estimate. It is based on an experimental method originally introduced by Robert Siegler & John Opfer (2003) to examine numerical estimation. Many subsequent studies have used the method to understand the estimation capabilities of children as they develop their numerical skills. A computerized version of the number line estimation test designed by the same team was used in the Canadian Count Me In longitudinal study. This iPad app was tested in the field in an experiment with pre-kindergarten children in 2011.
In the EstimationLine app, the line is shown with a 0 above the left end of the line and a configurable endpoint (usually 10, 100 or 1000) above the right end, with the stimulus or target number for each trial displayed above the line. The participant (usually a child) is asked to mark the location on the number line where they think that target number belongs. In this iPad app version, the child touches the number line with their finger to mark their estimate of the target location. A red vertical mark is displayed to show their estimate. A small 'Retry' button is shown with each trial, since small children occasionally make accidental touches.
EstimationLine spares the experimenter the considerable work of converting pencil marks on paper into usable output data files. The output data for each trial is written into a trial by trial file in CSV format. The files can be retrieved via iTunes. Each trial output includes the participant's identifying information and the endpoint, the stimuli that was displayed and the participant's estimate. The estimate is computed based on the endpoint and the location they touched. The estimate is shown with up to two decimal points. For example, on a trial with a stimuli target of 9, above a line with an endpoint of 10, the touched estimate was written out to the datafile as 8.56.
The app shows four configurable sets of target stimuli. Each set has two configurable aspects: a single endpoint for the entire set, and the group of target or stimuli numbers that will be shown as trials in the set. After each set of trials for a particular endpoint,, an option to continue to the next set is displayed for the experimenter, so that the number of sets can be adjusted for each child, based on either a predetermined design or on the child's performance.The endpoints can be modified for each set and like the stimuli, can also be pre-configured via iTunes.
The stimuli sets provided as app defaults increase in endpoint size, complexity and number of trials. These four sets of default target stimuli were created to cover the full range of development: from the pre-kindergarten children (endpoints of 10) to older grades five and six students (endpoints of 100 and 1000). Each set of stimuli can be modified to meet the experimenter's needs. The app randomly shuffles the target stimuli at the start of each set to randomize the display order of the trials. The end-points of the number lines for each set have default values of 10, 20, 100 and 100. End points can also be modified for each participant session.
This is the first screen displayed when the app is started. There are 3 fields for the experimenter to fill which will identify the participant's trials in the output file:
Once you have entered and made your selection, press the "Go" button on the keyboard.
There are four sets available for each participant, although all of the sets do not have to be administered. This screen allows the experimenter to modify the endpoint numbers (shown below the right-most end of the number line) for each set.
This screen displays the default set of instructions. Have the participant read it or read it aloud to them. Press the Continue button once the instructions have been understood.
The experiment opens with the number line visible on the screen with start and endpoint values. For each trial, the participant or experimenter touches the Go button (in green in the bottom control panel) to start the trial and display the target stimuli at the top of the screen. At this point, any touch near the line will drop the red vertical estimate bar to show the estimate for that trial. The red Done button is then clicked to confirm the completion of the trial. The trial process then repeats until the end of the set.
A small 'Retry' button is provided in the bottom control panel during a trial. This feature was added for the experimenter following pilot testing with very young childen, who occasionally accidentally touched the line, and wished to clear the estimate bar and try again.
At the end of a set of trials, the number line is cleared from the screen. The default question 'Continue to next set?' is displayed with NO and YES buttons. Touching the Yes button launches the next set of trials. Touching the 'No' button leads to the 'Done' screen, as described below.
Once the NO button has been selected to avoid continuing to further sets, or all four sets have been completed, the number line and control panel are removed and the word 'Done' is displayed. At this point, the iPad should be retrieved from the participant.
You can then press the View Scores button to see the results that have been saved into the data_v2.csv file. The results for the participant are displayed for each trial in each set they performed.
At this point, you can start a new participant via the button at the bottom of the screen or use another app by clicking the Home button on the iPad. Don't worry about 'closing' the EstimationLine app. Apps are normally left running - the concept of 'opening' and 'closing' is not applicable to apps.
The EstimationLine app was field-tested in a study of young children in daycare settings conducted by Jo-Anne LeFevre of Carleton University in October-November 2011. Experimenters in the study reported that the children enjoyed using the iPad and had no trouble touching the line. Some children in the study were already familiar with the iPad from home use. As expected, many of the young children performed only a single set, and even those trials often did not appear to reflect much knowledge of the number line.
The stimuli file 'stimuli-production.txt' contains 4 lines of target stimuli - one for each set. Set 1 of the default stimuli is deliberately short and simple - it could be used as a demonstration set, or as a test set to determine whether the child should proceed to the next set. Each set is 'shuffled' before it is displayed, so that the targets appear in a random order for each participant.
The stimuli sets are designed to provide balanced coverage of the number line and progress in difficulty to accomodate testing with very young children. However, your stimuli design will depend on the age-groups you are studying and the goals of the study. See below for instructions on how to customize stimuli files to set up different target stimuli for the sets.
|Set 1: 10,20,30,40,50,60,70,80,90|
|Set 2: 5,10,15,20,25,30,35,40,45,50,55,60,65,70,75,80,85,90,95|
|Set 3: 5,11,18,25,33,40,46,52,58,65,71,78,85,93,99|
|Set 4: 2,8,15,22,30,37,43,49,55,62,68,75,82,90,96|
Endpoints for set are configured separately from the set stimuli, because the endpoints can also be changed for each participant. The default endpoints built into the app for the four sets are shown below. They are presented in the order in which they are shown in the config.txt file - there is no randomization applied to the order of the sets. See instructions on how to customize stimuli files below to change the endpoints in the config.txt file.
defaultEnds:10, 20, 100, 100
Retrieve and Analyse Output Data
The File Sharing screen in iTunes:
The session data is stored the file named data_v2.csv. EstimationLine uses CSV format, with column headers on the first line, to allow for easy interoperation with programs like Excel and SPSS. Each row in the output file stores the data for one trial.
Information contained in the columns:
|id||the participant id|
|gender||gender, either m or f|
|birthyear||year of birth|
|trialtime||The time that the session ended. In the format "dd-mm-yyyy hh:mm"|
|endpoint||The endpoint used for the trial. I.E 10|
|selected||The number location on the line that the user touched to two decimal places of precision. On a scale from 0 to the endpoint.|
|stimuli||The stimuli number that the child was asked to show where it was.|
EstimationLine uses csv-format files for both input and output of the data. Once the app has been run at least once, the default configuration files become available in the iTunes file sharing section. Via iTunes, the default files can be saved to a computer, modified and then put back on the iPad, as described below.
Note: Due to a quirk in the iTunes process, you must have run the EstimationLine app at least once before the files become available via this method.
The config.txt file is a list of keys and values separated by colons. In the following format:
The keys have the following default settings:
|instructions||instructions.txt||The name of the text file with the instructions to the participant. These are shown to the participant before they start.|
|stimuliFile||stimuli-production.txt||The name of the text file with the stimuli. See the Changing the Stimuli section of this document.|
|defaultEnds||10,20,100,100||The default endpoints to use for the four sets, separated by commas.|
|doneButtonTitle||Done||The text displayed on the done button.|
|playButtonTitle||Go||The text displayed on the play button.|
|okText||Is this good?||The text displayed to ask the child if the location they think they touched the right place.|
|playText||Press the "Go" button to see the number.||The text displayed on the bottom bar to ask if the child is ready.|
|whereIsText||Where Is||The text displayed next to the stimuli number asking where it should go on the line.|
|nextTrialQuestion||Continue to the next set?||The text displayed on a screen asking if the experimenter wants to continue to the next set.|
The stimuli file is the file that describes the numbers that the child is shown for each trial. The file contains 4 lines, one line for each of the four sets. Each line is a comma-separated list of percentages along the line. Percentages are used so that the same stimuli can be used while allowing the endpoints to be changed at the start of every trial.
Note: percentages may be decimal/real numbers if necessary. For example, 43.23487 is a valid stimuli. However, the precision is limited by the iPad's hardware so arbitrary precision is not possible.
Percentages are converted to integer stimuli before running the trial based on the endpoint being used. For example: target stimuli percentage 20 would be displayed as 2 for an endpoint of 10, 4 for an endpoint of 20, or 200 for an endpoint of 1000. Since the result of the transformation is rounded, extra precision can be added to the stimuli for larger endpoints but it will be rounded for smaller endpoints. For example: the stimuli percentage 67.94 would be displayed as 7 for an endpoint of 10, 68 for an endpoint of 100 and 6794 for an endpoint of 10,000.
The default configuration file is named stimuli-production.txt and looks like this:
10,20,30,40,50,60,70,80,90 5,10,15,20,25,30,35,40,45,50,55,60,65,70,75,80,85,90,95 5,11,18,25,33,40,46,52,58,65,71,78,85,93,99 2,8,15,22,30,37,43,49,55,62,68,75,82,90,96
To use a completely new set of sequences:
Customizing the instructions shown at the beginning of the task can be done simply by uploading a text file containing your instructions.
© Tristan Hume 2012.