Biostats Calculator

News

2009-10-14 - Version 1.2 has been submitted to Apple and should appear on the App Store in the next few weeks. This version greatly improves data entry, adds the Yates correction for chi-square tests, improves look and feel, and fixes some bugs.

2009-10-01 - Version 1.1 is live on the App Store. This version adds an ANOVA test, some user interface improvements, and a speed boost.

Version history

Biostats Calculator is under active development and I am constantly looking for ways to improve its functionality and usability. Updates to new versions are automatic and free of charge. Here is what's been in each release:

1.2 (pending release)

feature: added decimal point (.) and minus (-) buttons to the numeric keypad - it can now be used for all data entry

feature: Added 'enter' button to keypad to advance to the next field or insert the current row, for much faster data entry.

feature: p-values are now displayed in a consistent location and color coded. Confidence intervals are no longer color coded.

feature: chi-square test now provides yates-corrected values for 2x2 tables with entries that are 5 or less

change: test screens are more colourful and attractive

change: bubbles pop up further away from your finger, allowing you to see them more easily

change: keyboard no longer obscures newly added entries of long tables

bugfix: corrected typo in ANOVA help screen

bugfix: keyboard for paired t-test, mann-whitney u, and ANOVA allows decimals to be entered

1.1

feature: one-way ANOVA test

feature: tests are loaded on demand to decrease application load time and memory consumption

change: added more colour to test screens to highlight the text entry fields

bugfix: fixed some blurred text on test screens and menu

bugfix: fixed animation issue in the title bar when transitioning between screens

bugfix: 'i' button appears in top-right of help screen to indicate titlebar is clickable

1.0.2

feature: touch-and-hold balloon help explanations now available for all labels on application screens

feature: intermediate statistics such as t-statistic and chi-square values now available via touch-and-hold balloon help

change: odds ratio explained using a more useful and intuitive interpretation

bugfix: it is no longer possible to enter negative values for standard deviation, or percentages outside the 0-100% range

1.0.2b2

feature: balloon help now available for some labels and output areas. (very incomplete, for testing the technical changes)

1.0.2b1

bugfix: the sample size calculator now uses the % group size that is shown when you select it (e.g. 20%) rather than an unrounded value (e.g. 20.2%).

change: 'effect proportion in each group' changed to 'outcome proportion in each group' on sample size calculator (categorical)

feature: added Number Needed to Treat calculations on the relative risk screen

change: added acknowledgements to main application help

1.0.1

bugfix: fixed case where a value could get 'stuck' in a text field as a default, until the screen was cleared

feature: added help screen for main menu

change: help screens are now accessed by tapping the title bar

change: data now added by pressing green + button rather than blue 'add contact' button

change: paired t-test now shows mean(sd) for samples and for difference

change: wilcoxon signed-rank test shows median and range for groups

change: wilcoxon signed-rank test and t-test displays differences as group2-group1 (used to be vice versa)

change: support site shifted to abstractable.net

bugfix: fixed misaligned text fields on unpaired t-test and mann-whitney u test

change: increased row spacing for mann-whitney u data entry

1.0.1b1

bugfix: fixed memory leak in t-test

bugfix: fixed memory leak in paired t-test

change: changed 'risk factor' to 'exposure' for odds ratio and relative risk

change: changed 'affected'/'unaffected' to 'outcome +'/'outcome -' for relative risk

change: changed 'positive'/'negative' to 'present'/'absent' for chi-square test

change: technical edits to help text

1.0 - 2009-07-24

first public release

change: diagnostic tests - UI overhauled

feature: diagnostic tests - totals now shown on the 2x2 table

change: diagnostic tests - values shown as percentages where applicable

feature: diagnostic tests - positive and negative error rates added

change: small p values display as "< 0.0005" instead of "0.000"

change: pearson correlation statistic renamed from R to r

change: spearman correlation statistic renamed from ρ to r_s

change: standardised on "p value" over "p-value" for consistency

change: sample size calculator doesn't distinguish between case/control and trial, just gives the larger size (difference is small)

bugfix: help pages added for sample size calculator and diagnostic tests

0.12 - 2009-07-24

feature: help pages. all screens except sample size and diagnostic tests have them

0.11 - 2009-07-23

feature: sample size calculator for numeric data

feature: diagnostic utility calculator

feature: pearson correlation

feature: spearman rank correlation

feature: odds ratio and relative risk give p values

bugfix: doesn't crash when clearing screen in sample size calculator

change: moved '+' buttons away from titlebar slightly

bugfix: 'clear data' clears input boxes in t-test etc

change: when '+' is pressed on a paired-data screen with the second field focused, the first field will become focused

change: new app icon and name

bugfix: app icon shows up in iTunes for ad-hoc provisioned users

0.10 - 2009-07-22

First internal release

pre-0.10 - 2009-06 and 2009-07

Various simulator-only versions and proofs of concept