Descriptive Statistics

1. Descriptive Statistics Prepared by: Asma Qassim Al-jawarneh Ati Sardarinejad Reem Suliman Dr. Balakrishnan MuniandyPTPM-USM

2. What Is Statistics? Statistics is a collection of tools used for converting raw data into information to help decision makers in their works. Descriptive statistics are numerical estimates that organize and sum up or present the data. Inferential statistics is the process of inferring from a sample to the population.

3. Descriptive Statistics

4. Concept & definition • Describing data with tables and graphs like; frequency polygon, pie chart. • Mathematical methods (such as mean, median, standard deviation) that summarize and interpret some of the properties of a set of data (sample) but do not infer the properties of the population from which the sample was drawn.

5. Concept & definition (cond.) • Descriptive statistics aim to describe the midpoint of a spread of scores, usually referred to as the measure of central tendency, and the spread of scores known as the dispersion or variance.

6. Descriptive Measures • Central Tendency measures. They are computed to give a “center” around which the measurements in the data are distributed. 1. Mean: Sum of the values divided by the number of cases ex. : 2,4,6,8 Mean=(2+4+6+8)/4=5 2. Median: represents the middle of the ordered sample data ex. : 1,2,3,4,5 Median= 3 ex. : 1,3,4,6,9,12,16,19 Median= (6+9)/2= 7.5 3. Mode: is the value that occurs most frequently ex. 3,4,5,5,6,8,9,9,9 Mode= 9

7. Descriptive Measures (cond.) • Variation or Variability measures. indices enabling the researcher to indicate how spread out a group of scores are. 1.Range:the difference between the highest and lowest score in a distribution. Range= 60-32=28

8. Descriptive Measures (cond.) 2. variation (s2 )is the sum of the squared deviations from the mean divided by the number of cases minus 1. 3. Standard deviation (s) is the square root of the variance.

9. When use DS • When you describe your databases or the relationships between your variables. • when a researcher wants to gain a better understanding of a topic. • The idea behind this type of research is to study frequencies, averages, and other statistical calculations. • In medical and nursing situations.

10. Use in statistical analyses • Descriptive statistics provide simple summaries about the sample and the measures. ex.: the grade point average for many students. This single number describes the general performance of a student across the range of their course experiences. - The percentage summarizes or describes multiple discrete events. • Describing a large set of observations with a single indicator risks distorting the original data or losing important detail. the GPA doesn't tell you whether the student was in difficult or easy courses. • Despite these limitations, descriptive statistics provide a powerful summary that may enable comparisons across people or other units

11. Research Article • Title: Nursing Students’ Reading and English Aptitudes and Their Relationship to Discipline-Specific Formal Writing Ability: A Descriptive Correlational Study. • Problem statement: writing apprehension is a common phenomenon among nursing students. • Purpose of the study: to describe writing apprehension and to assess the relationships among reading and English aptitude and discipline-specific formal writing ability among undergraduate nursing students.

12. Research Article (cond.) • Sample: 146 sophomores nursing students. • Instruments: Test of Essential Academic Skills (TEAS). • Result: - DESCRIPTION OF THE SAMPLE The sample consisted of 146 sophomore nursing students from two admission cohorts. Each cohort was comprised of 73 students. Three students (2 percent) had English as their second language. - Descriptive statistics were calculated regarding reading and English aptitudes. Reading aptitudes (M = 89.7) were higher than English aptitudes (M = 80.6).

13. Research Article (cond.)

14. Research Article (cond.) • Results: - The results indicated that undergraduate nursing students’ reading aptitudes were higher than their English aptitudes, and that English aptitude was more predictive of formal writing ability than was reading aptitude. - TEAS English subtest addresses areas more directly related to writing (e.g., punctuation, grammar, sentence structure, and spelling) than does the reading subtest (e.g., paragraph comprehension, passage comprehension, inferences/conclusions).

15. Conclusion • Descriptive analyses are likely the most simple of statistical analysis to perform and to interpret. • permit the researcher to describe many pieces of data with a few indices • Descriptive statistics provide us with a useful strategy for summarizing data and providing a description of the sample but cannot provide information for causal analysis. Analysis of data that allows us to generalize from a sample to a larger population requires the use of inferential statistics.

16. References • Fisher, M. J. and A. P. Marshall (2009). Understanding descriptive statistics. Australian Critical Care22(2): 93-97. • Newton, S. and G. Moore (2010). Nursing Students' Reading and English Aptitudes and Their Relationship to Discipline-Specific Formal Writing Ability: A Descriptive Correlational Study. Nursing Education Perspectives 31(4): 221-225. • http://www.answers.com/topic/descriptive-statistics#ixzz1F2IvSG9a

17. Thank you