Biostats Calculator

News

2010-10-01 - Version 1.3 has been submitted to the App Store. This version adds iPad support and fixed numeric input on iOS 4.

2009-10-14 - Version 1.2 is live on the App Store. 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:

1.3 (pending release)

feature: iPad support, both landscape and portrait orientation.

bugfix: removed custom keypad with dot (.) and minus (-) buttons, it was incompatible with iOS 4 and iPad.

bugfix: corrected inconsistent number formatting with certain locale settings.

1.2

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