Statistics is a branch of mathematics that deals with the collection, organization, analysis, interpretation, and presentation of data. In nursing research, statistics help convert raw data into meaningful conclusions to guide clinical practice, education, administration, and policy-making.
1. Croxton and Cowden (1973):
โStatistics is the science which deals with the collection, presentation, analysis and interpretation of numerical data.โ
2. Babbie (2001):
โStatistics is a set of methods used to describe, organize, and interpret quantitative data.โ
3. Polit & Beck (Nursing Research Experts):
โStatistics is a tool that enables nurse researchers to make sense of quantitative information and to draw valid conclusions.โ
Study: A study to evaluate the effectiveness of a health education program on hand hygiene.
Statistics is the science of collecting, organizing, analyzing, interpreting, and presenting data in a meaningful way. In nursing, statistics play a vital role in clinical decision-making, patient care, quality improvement, research, and education. Through the use of statistics, nurses can transform numerical data into evidence-based practice that improves outcomes and enhances healthcare delivery.
Descriptive statistics help to summarize, simplify, and describe data from patients or studies.
Inferential statistics allow nurses and researchers to analyze sample data and make generalizations about a larger population. It helps determine whether differences or relationships in data are statistically significant.
Statistical tests help explore associations or dependencies between two or more variables.
Statistics support evidence-based nursing, allowing clinical decisions to be based on scientific data rather than assumptions or tradition.
Statistics are used to monitor and improve nursing services and patient outcomes.
Statistics help evaluate student performance, teaching methods, and nursing programs.
Statistics support planning and implementation of community health programs.
Statistical summaries are essential for creating hospital reports, health policies, and research publications.
Title: A study to evaluate the effectiveness of structured teaching on hand hygiene among nursing students
Variable | Pre-test Mean | Post-test Mean | t-value | p-value |
---|---|---|---|---|
Knowledge Score | 7.8 ยฑ 2.1 | 14.5 ยฑ 2.3 | 8.65 | < 0.001 |
The statistically significant result (p < 0.001) confirms that the teaching intervention substantially improved knowledge. This supports the hypothesis and demonstrates the effectiveness of educational strategies in nursing.
Purpose | Tools |
---|---|
Measure of Central Tendency | Mean, Median, Mode |
Measure of Dispersion | Range, Variance, Standard Deviation |
Relationship | Correlation, Regression |
Comparison | t-test, ANOVA |
Categorical Analysis | Chi-square test |
Rating Scales | Likert scale, Semantic differential scale |
The use of statistics in nursing is fundamental to ensure safe, effective, and evidence-based care. Whether it’s in clinical practice, education, community health, or research, statistics help nurses:
Scales of measurement refer to the different ways variables can be categorized, measured, and interpreted. They determine what kind of statistical analysis is appropriate for the data collected.
๐ Definition:
โA scale of measurement refers to a system for assigning numbers or labels to variables to represent quantities or qualities of attributes.โ
โ Polit & Beck
There are four main types, arranged in increasing order of complexity and precision:
๐ธ Use in Nursing: Categorizing patient diagnoses, departments, or ethnic groups.
๐ธ Use in Nursing: Pain assessment scales, triage categories in emergency care.
๐ธ Use in Nursing: Tracking body temperature changes over time.
๐ธ Use in Nursing: Measuring vitals, lab values, dosage, fluid intake/output.
Scale | Nature of Data | Order | Equal Interval | True Zero | Examples |
---|---|---|---|---|---|
Nominal | Categorical | โ | โ | โ | Gender, Blood Group |
Ordinal | Ranked | โ | โ | โ | Pain Level, Satisfaction |
Interval | Numerical | โ | โ | โ | Temperature (ยฐC), IQ |
Ratio | Numerical | โ | โ | โ | BP, Weight, Age |
Objective: To assess the effectiveness of a pain management intervention.
Variable | Scale of Measurement |
---|---|
Pain intensity | Ordinal |
Age of patient | Ratio |
Gender | Nominal |
Temperature | Interval |
Understanding the scales of measurement is essential for selecting the right statistical methods, ensuring accurate data interpretation, and drawing valid conclusions in nursing research. Each scale provides a different level of detail and influences how data can be analyzed.
Frequency distribution is a systematic arrangement of data that shows how often (i.e., the frequency) each value or group of values occurs in a dataset.
๐ Definition:
โA frequency distribution is a tabular summary that shows the number of times each value (or range of values) of a variable occurs in a dataset.โ
โ Polit & Beck
Shows how many times each individual value occurs.
Example: Number of patients reporting different pain scores.
Pain Score | Frequency (No. of Patients) |
---|---|
0 | 2 |
1 | 4 |
2 | 6 |
3 | 10 |
4 | 8 |
Used when data is continuous and values are grouped into intervals.
Example: Age distribution of 50 patients.
Age Group (Years) | Frequency |
---|---|
10โ19 | 4 |
20โ29 | 12 |
30โ39 | 16 |
40โ49 | 10 |
50โ59 | 8 |
Shows the percentage of observations in each class instead of actual frequency.
Example:
Age Group | Frequency | Relative Frequency (%) |
---|---|---|
20โ29 | 12 | 24% |
30โ39 | 16 | 32% |
โฆ | โฆ | โฆ |
Shows the accumulated frequency up to a certain value or class.
Example:
Age Group | Frequency | Cumulative Frequency |
---|---|---|
10โ19 | 4 | 4 |
20โ29 | 12 | 16 |
30โ39 | 16 | 32 |
40โ49 | 10 | 42 |
50โ59 | 8 | 50 |
Study: Frequency of urinary tract infection (UTI) in different age groups among females.
Age Group (Years) | No. of UTI Cases |
---|---|
15โ24 | 18 |
25โ34 | 26 |
35โ44 | 22 |
45โ54 | 14 |
55โ64 | 10 |
โ A bar chart or histogram can be used to display this data visually in your research report.
Frequency distribution is one of the most basic and essential tools in nursing research. It helps to organize and simplify data, making it easier to interpret trends and prepare for statistical analysis. Whether you’re studying patient demographics, symptoms, or treatment outcomes, frequency tables bring clarity to your findings.
Graphical presentation of data refers to the use of visual tools like charts, graphs, and diagrams to represent data in a way that is easy to understand, compare, and analyze.
๐ Definition:
โGraphical presentation is a method of displaying statistical data visually using charts, diagrams, or plots to reveal patterns, trends, and relationships clearly and effectively.โ
โ Polit & Beck
| Data Type | Gender, Diagnosis, Department
| Used For | Simple comparisons between groups
| Key Tip | Equal space between bars
| Data Type | Continuous numerical
| Used For | Distribution over intervals
| Key Tip | Use equal class intervals
| Data Type | Proportions
| Used For | Showing part-to-whole relationships
| Key Tip | Total should be 100%
| Data Type | Continuous or time-series
| Used For | Monitoring trends or changes
| Key Tip | Use when data varies with time
| Data Type | Categorical
| Used For | Community presentations
| Key Tip | Keep symbols consistent and clearly labeled
| Data Type | Paired numerical
| Used For | Identifying relationships or correlation
| Key Tip | Add a trend line if needed
Type of Data | Best Graph Type |
---|---|
Categorical (e.g., gender) | Bar Chart or Pie Chart |
Continuous (e.g., age) | Histogram or Line Graph |
Proportional Data | Pie Chart |
Relationship Data | Scatter Plot |
Time-series Data | Line Graph |
Title: A study to assess the effectiveness of health teaching on anemia prevention among adolescent girls
Graphical Presentations:
The graphical presentation of data transforms statistical findings into visual stories that are easier to understand, interpret, and communicate. In nursing research, graphs are essential to convey results to educators, clinicians, policymakers, and even patients.
Comparison of Knowledge Levels: Pre-test vs Post-test
Pre-test Knowledge Level Distribution
Post-test Knowledge Level Distribution
The mean is the arithmetic average of a set of values. It represents the central value of the data.
๐ Formula:
Mean (๐ฅฬ) = ฮฃx / n
(Sum of all values รท Number of values)
Suppose systolic BP readings of 5 patients are:
120, 122, 124, 126, 128
Mean = (120 + 122 + 124 + 126 + 128) / 5 = 124 mmHg
The median is the middle value in an ordered dataset. It divides the data into two equal halves.
๐ If odd number of values: Middle value
If even number of values: Average of two middle values
Patient heart rates: 78, 80, 82, 84, 86
Median = 82 bpm (3rd value)
If: 78, 80, 82, 84
Median = (80 + 82) / 2 = 81 bpm
The mode is the value that appears most frequently in a dataset.
A dataset may have no mode, one mode (unimodal), or more than one mode (bimodal/multimodal).
Pain scores: 3, 4, 4, 5, 6, 4, 7
Mode = 4 (occurs 3 times)
Standard Deviation measures the amount of variation or dispersion in a set of values.
๐ Formula:
SD = โฮฃ(x – ๐ฅฬ)ยฒ / n
(Square root of average squared deviation from the mean)
Two classes score the same mean of 70 in an exam:
Class A Scores | SD = 2 (Scores are: 68, 69, 70, 71, 72) |
---|---|
Class B Scores | SD = 10 (Scores are: 55, 60, 70, 80, 85) |
Even with same mean, Class B has more variability.
Measure | Definition | Best Use |
---|---|---|
Mean | Arithmetic average | Normally distributed data |
Median | Middle value | Skewed data or outliers present |
Mode | Most frequent value | Categorical or nominal data |
Standard Deviation | Dispersion of values from the mean | Measuring consistency/variability |
Study Title: Effect of health education on knowledge of anemia prevention
Variable | Mean Score | Median | Mode | SD |
---|---|---|---|---|
Pre-test Score | 7.8 | 8 | 8 | 2.1 |
Post-test Score | 14.6 | 15 | 15 | 1.9 |
Interpretation:
The post-test mean and median are higher, showing improved knowledge. A lower SD post-test indicates more consistency in knowledge gained.
Understanding mean, median, mode, and standard deviation allows nurse researchers to:
A Normal Probability Distribution, also called the Normal Distribution or Bell Curve, is a statistical model where most of the values cluster around the mean (average), and the probabilities decrease symmetrically as values move away from the mean.
๐ Definition:
โThe normal distribution is a symmetrical, bell-shaped curve that describes the distribution of many types of data. Most values cluster around a central mean with symmetrical tapering toward the extremes.โ
Feature | Description |
---|---|
Symmetrical Shape | Left and right sides are mirror images |
Mean = Median = Mode | All central tendencies lie at the center |
Bell-shaped Curve | Data tapers off evenly on both sides |
Empirical Rule Applies | 68โ95โ99.7 Rule (see below) |
Total Area Under Curve = 1 | Represents 100% probability |
In a normal distribution:
๐ง Example: If the average systolic BP is 120 mmHg with SD = 10
- 68% of readings are between 110โ130
- 95% are between 100โ140
- 99.7% are between 90โ150
Variable | Usually Follows Normal Distribution? | Explanation |
---|---|---|
Blood pressure (in healthy adults) | โ Yes | Most people have values near the average |
Body temperature | โ Yes | Varies slightly around the normal (98.6ยฐF) |
Wound healing time | โ Often No | May be skewed based on severity |
Length of hospital stay | โ Often No | Positively skewed due to a few long-stay patients |
A normal distribution curve:
Would you like me to generate a visual bell curve using sample nursing data?
Normal Distribution Function
Where:
The normal probability distribution is a fundamental concept in statistics, forming the backbone of many tests and tools used in nursing research. It helps researchers:
Understanding this concept ensures accurate analysis and supports evidence-based nursing practice.
Bell Curve: Normal Distribution of Sample Data
Here is your Bell Curve Chart representing a normal distribution with a mean of 100 and standard deviation of 15 โ often used for test scores or physiological data in nursing research.
Tests of significance are statistical procedures used to determine whether the differences observed in data (between groups, before and after intervention, etc.) are due to chance or are statistically meaningful.
๐ Definition:
โA test of significance is a procedure used to assess whether the observed differences in data are unlikely to have occurred by chance alone.โ
Term | Meaning |
---|---|
Null Hypothesis (Hโ) | Assumes no difference or effect |
Alternative Hypothesis (Hโ) | Assumes a real difference or effect |
p-value | Probability that results occurred by chance |
Level of Significance (ฮฑ) | Commonly set at 0.05 (5%) or 0.01 (1%) |
If p < ฮฑ | Reject the null hypothesis โ result is significant |
Test Name | Use Case | Data Type | Example in Nursing |
---|---|---|---|
t-test | Compare means of two groups | Interval/Ratio | Pre-test vs Post-test knowledge scores |
Chi-square test | Compare proportions/frequencies | Nominal/Categorical | Male vs Female patients with diabetes |
ANOVA | Compare means of 3 or more groups | Interval/Ratio | Comparing satisfaction scores in 3 wards |
Z-test | Compare sample mean to population mean | Large samples | Comparing national and local MMR |
Correlation (r) | Measures relationship between two variables | Interval/Ratio | Stress vs Sleep quality |
Regression | Predict value of one variable based on another | Interval/Ratio | Predicting BP based on BMI |
Study: Effectiveness of a structured teaching program on knowledge about anemia
Test Used | t-test |
---|---|
Mean Pre-test Score | 7.8 |
Mean Post-test Score | 14.6 |
p-value | 0.001 |
๐ Interpretation:
Since p < 0.05, the difference is statistically significant. The teaching program was effective.
ฮฑ Level | Confidence Level | Interpretation |
---|---|---|
0.05 | 95% | 5% chance results are due to random variation |
0.01 | 99% | More stringent; used in critical research |
Tests of significance are essential for determining whether the findings in nursing research are real or due to chance. They form the statistical foundation for evidence-based practice, helping researchers make valid, reliable, and informed conclusions.
t-test Visual: Knowledge Levels Before and After Intervention
Chi-square Visual: Smoking vs Disease Incidence
The coefficient of correlation is a statistical measure that indicates the strength and direction of a relationship between two variables.
๐ Definition:
โCorrelation is a statistical technique used to determine the degree to which two variables are related.โ
โ Polit & Beck
Value of r | Interpretation |
---|---|
+1 | Perfect positive correlation |
0 | No correlation |
โ1 | Perfect negative correlation |
Between 0.70 to 0.99 | Strong correlation |
Between 0.40 to 0.69 | Moderate correlation |
Between 0.10 to 0.39 | Weak correlation |
Type | Description |
---|---|
Positive Correlation | As one variable increases, the other also increases. |
Negative Correlation | As one variable increases, the other decreases. |
Zero Correlation | No relationship between variables. |
Variable 1 | Variable 2 | Type of Correlation |
---|---|---|
Study hours | Exam performance | Positive correlation |
Stress level | Sleep duration | Negative correlation |
Height of patients | Blood group type | Zero correlation |
Pearson’s Correlation Coefficient Formula
You can also use software like Excel, SPSS, or calculators to compute it.
Title: Correlation between stress levels and quality of sleep among nursing students
The coefficient of correlation helps nurse researchers understand how two health-related variables move together. It is a powerful tool to guide interventions, assessments, and research decisions, especially when identifying risk factors or evaluating outcomes.
Statistical packages are specialized software programs designed to help researchers perform data analysis, including descriptive and inferential statistics, graphing, and report generation.
๐ Definition:
โA statistical package is a computer program used for collecting, organizing, analyzing, interpreting, and presenting data using statistical methods.โ
Software | Full Form / Developer | Key Features | Application in Nursing |
---|---|---|---|
SPSS | Statistical Package for the Social Sciences (IBM) | User-friendly interface, menu-based commands | Widely used in nursing thesis, projects, and institutional research |
Excel | Microsoft Excel | Basic stats, formulas, charts | Useful for small datasets, data entry, and graphing |
R | Open-source programming language | Advanced, flexible, free | Used in complex nursing research by statisticians |
STATA | Data Analysis and Statistical Software | Strong in longitudinal & econometric data | Healthcare research, epidemiology |
SAS | Statistical Analysis System | High-end analytics | Clinical trials, hospital data systems |
MINITAB | โ | Educational & industrial stats | Teaching basic stats to nursing students |
GraphPad Prism | โ | Graphs and bio-statistical tests | Useful in pharmacology, physiology, lab-based studies |
Research Task | Software Used | Explanation |
---|---|---|
Comparing pre-test and post-test scores | SPSS (t-test) | Evaluates effectiveness of a health teaching program |
Plotting patient admission trends | Excel (Line Chart) | Visualizes monthly hospital data |
Calculating mean BP of hypertensive patients | SPSS or Excel | Summary statistics of clinical data |
Analyzing infection rates between wards | SPSS (Chi-square test) | Determines association |
Correlation between stress and sleep | SPSS or R | Pearsonโs r or regression analysis |
Statistical packages are powerful tools that empower nursing researchers to analyze data accurately, draw valid conclusions, and present findings effectively. Whether you are conducting a community survey, clinical study, or student project, the proper use of statistical software enhances the quality and credibility of your research
To test whether there is a significant mean difference between two related (paired) scores โ like before and after a health education session.
Pre-test and post-test knowledge scores of 30 nursing students.
Pre_test
, Post_test
Pre_test
and Post_test
to the โPaired Variablesโ box.Output | Meaning |
---|---|
Mean Difference | How much average score changed |
t-value | Test statistic |
Sig. (2-tailed) | p-value (if p < 0.05 โ significant) |
โ If p = 0.001 โ the intervention was statistically significant
To compare the means of two different groups, e.g., male vs female nurses’ stress scores.
Stress_Score
)Gender
โ Male/Female)Stress_Score
Gender
โ If p < 0.05 โ significant difference between the groups
To check for an association between two categorical variables, e.g., smoking status vs lung disease.
Smoking
(Yes/No)Lung_Disease
(Yes/No)Smoking
Lung_Disease
โ E.g., p = 0.002 โ smoking and lung disease are significantly associated