University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

409

Pages:

2
Author:

Mariam A. A.

Stats for Doctors Lesson One Introduction • Representative sample: achieved by random selection (each member of the population has an equal chance of being sampled) – looking at entire population would be: impossible, costly, time and labour intensive • Variables: characteristics that can take on a number of different values 13 • Values: possible numbers or categories that a variable can have • Score: particular value on a variable • Statistic: e.g. maximum value • Descriptive statisics (DS): summarises and describes a group of numbers such as the results of a research study 🡪 satisfies the broad curiosity driving an ongoing study • Inferential statistics (IS): attempts to create conclusions that are based on numbers from a research study but reach beyond the data observed 🡪 satisfies specific questions raised prior to the study Numerical variables • Interval: variables that have constant, equal distances between values, no true zero o IQ test 🡪 140 is not necessarily double as intelligent as 70 + 0 point is arbitrary • Ratio: variables have equal intervals between values, 0 point is meaningful, numerical relationships between numbers is meaningful o Weight 🡪 someone who weighs 100ks is twice as heavy as someone who weighs 50kg o In statistical analysis, interval and ratio data can be treated as continuous data • Discrete (data you can count): numerical variables counted in a data set – usually whole number o Number of children in household o Number of relapses in the past year/ hospital admissions/ cigarettes smoked per day • Continuous (data you can calculate/measure): variables that can theoretically take on an infinite number of values o Height, weight, HR, BP, cholesterol, age, temperature o Both interval and ratio data can be continuous • Note: numerical data can sometimes be collapsed/grouped into categorical data 14 Application: Other types of data • Ranks – relative position of the members of a group e.g. intern 🡪 resident... 🡪 senior staff specialist • Percentages e.g. body fat percentage, ejection fraction (most commonly refers to left ventricular ejection fraction [LVED] – blood pumped out of left ventricle with each contraction) • Apgar score – evaluates a newborn’s physical condition and ranges between 0 (worst possible condition) and 10 (best possible condition) 🡪 given at 1 and 5 minutes after birth o Appearance (skin colour) o Pulse (HR) o Grimace response (reflexes) o Activity (muscle tone) o Respiration (breathing rate and effort) • Rate – HR (normal = 60-100/min for adults), perinatal mortality per 1000 births, respiratory rate 15 Presenting data • Continuous – histograms, box plot, line graphs o Histogram: no gap between bars, frequencies labelled across vertical axis, continuous variable labelled across horizontal axis