Statistical Table & Statistical
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Statistical Table & Statistical Graph. Zhang Guozhen School of Public Health Xinjiang Medical University. Statistical Tables and Graphs. Statistical description is a kind of fundamental work for statistical inference, which describes the feature of the sample.

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Statistical Table & Statistical Graph

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Statistical tables and graphs

Statistical Table & StatisticalGraph

Zhang Guozhen

School of Public Health

Xinjiang Medical University


Statistical tables and graphs

Statistical Tables and Graphs

  • Statistical description is a kind of fundamental work for statistical inference, which describes the feature of the sample.

  • The main forms for description are tables, graphs and numerical indexes.

  • Statistical tables and graphs are two kinds of forms made of point, line, area and number.

  • They can show the information of data directly. So they are widely used in medical practice.


Statistical tables and graphs

§1 Statistical Tables


Statistical tables

Statistical Tables

Example1 125 children were tested in county B and 9 cases were found In this study, 221 children were tested in county A and 4 cases were found suffering from rachitis; the prevalence rate was 18.10 per thousand.; the prevalence rate was 72.00 per thousand. 248 children were tested in county C and 2 cases were found; the prevalence rate was 8.00 per thousand…..

  • Very tired and verbose.

  • Difficult to remain any impression


Put into a table

Put into a table

Table 1 Rachiotis prevalence rates in 5 counties

  • Clearimpression !

    • Easy to compare each other !


Principles of making tables

Principles of Making Tables

  • The main contents must be emphasized, simple and understood easily.

  • Primary and secondary contents as well as arrangement must be clear


Construction of statistical table

Construction of Statistical Table

  • Title:generalize the contents, including time and site. The title is located on the top of the table and a sequence No. is on the left of the title.

  • Horizontal item:indicate the subjects investigated, usually located in the left of the table.

  • Vertical item:indicate statistical index including the units, usually located in the right and upper of the table.


Statistical tables and graphs

Table 1 Rachiotis prevalence rates in 5 counties


Statistical tables and graphs

  • Lines (horizontal only):

    • Top and bottom (dark): define the range of table

    • Others (light): separate items and figures.

    • Not suitable to having too many lines. The vertical lines and skew lines can’t be allowed.

  • Figures:require to use Arabian number in the statistical table and the decimal must be accordant. The empty cells can’t be allowed.

  • Notes:usually use star mark “  ” to express notes,

    and the mark “  ” usually put on the bottom of

    the table.


Basic structure of statistical table

Basic Structure of Statistical Table

Table 1 Table title

Top line

Item line

Total line

Bottom line


Types of statistical tables

Types of Statistical tables

  • Simple table:One variable only

  • Combinative table: More than 2 variables


Simple table

Simple Table

  • Row item: Subject

  • Column item: Predicate

  • The table read as:

  • The group of HBsAg carriers has 1457 persons tested, among which 46 positive with positive rate 3.16%.

  • 2. The group of HB patients has 1224 persons tested, among which 161 positive with positive rate 13.15%.


Combinative table

Combinative Table


Statistical tables and graphs

Table 4 the result of HBsAg of persons at different age group in city or country at certain area in certain year


Announcements of making statistical table

Announcements of Making Statistical Table

Example 2

The mental score and other factors related to coronary heart disease were researched in certain area. The results were shown in table 5


Table 5 compare of the risk factor of patients with coronary heart disease

Table 5 compare of the risk factor of patients with coronary heart disease


Problems in above table

Problems in above Table

  • Too much content was put in a table, especially, the measurement data and numeration data were put in a table.

  • Many blank space in table because of incompatible content in different column.

  • Inversion of row item and column item

  • Too much content, complex ranks, data inappropriately arranged in table


Table 6 compare of the risk factor of patients with coronary heart disease x s

Table 6 compare of the risk factor of patients with coronary heart disease (X±S)

Solution:dividing it into two tables, table 6,7


Table 7 compare of the risk factor of patients with coronary heart disease

Table 7 compare of the risk factor of patients with coronary heart disease


Frequent mistakes in tables

Frequent Mistakes in Tables

  • Title: Not exactly fit the content

  • Content:

    Too much;

    Mix of important and many non-important ones

  • Items:Inappropriately arranged

  • Figures:

    Total and subtotals; Digits and decimals

  • Lines: Using vertical lines and oblique lines


Statistical tables and graphs

What’s wrong with the following table?


Statistical tables and graphs

§2 Statistical Graphs


Statistical graphs

Statistical Graphs

  • advantage: data visualization and remaining impression.

  • The purpose of using graphic displays is to give a quick overall impression of the data, which is sometimes difficult to obtain with numeric measures.


Statistical tables and graphs

type:Different graphs according to different purposes and types of data

bar graph, histogram, percent bar chart,

pie chart, line graph, scatter plot ,statistical map, stem-leaf plot, box plot, residual plot


Statistical tables and graphs

Basic requirements:

  • Axis: Y-axis (vertical) and X-axis (horizontal).

  • Legend:explain meaning of colors or patterns.

  • Title:under the graph; content, time, place.


Statistical tables and graphs

Principle

  • Select the proper graph according to different aim of study and the character or feature of data.

  • Title: including time , place and main content .

    below the graph


Statistical tables and graphs

  • Index and unit are shown in the Y-axis and X-axis. The point of intersection commonly is 0. The ratio of Y-axis to X-axis is 5:7 properly.

  • Different lines and colors indicate different statistical value of subjects. Marginal data is attached to the graph.

  • Legends are the notes of a statistical graph, usually located on the right top corner or located between the bottom of the graph and the title.


Basic structure of a statistical graph

Basic Structure of a Statistical Graph

legend

Vertical item (unit)

legend

Graph body

0

Horizontal item (unit)

Fig 1 The basic structure of a statistical graph


Content

Content

  • bar chart

  • pie chart

  • percent bar chart

  • line graph

  • Histogram

  • Scatter Diagram


Bar chart

Bar Chart

  • Compare figures of different populations

  • Display the comparison among similar and relative independent data

  • Often used to compare the level of the variable at several locations

  • simple bar chart or complex bar chart


Statistical tables and graphs

Example 3 Mortality rates of main cause of death are shown in figure 1.

Bar chart is selected because the cause of death is interdependent indexes. Simple bar chart , only classified by the cause of death .


Statistical tables and graphs

Figure 2 mortality rate of main cause of death (/100,000)


Statistical tables and graphs

Fig.3 Average cost of outpatients for several treatments in a hospital in 1994 and 1997


Guidelines for bar charts

Guidelines for Bar Charts

  • Label both axes clearly

  • Leave space between bars

  • Leave space between the left-most bar and the vertical axis

  • When possible, begin the vertical axis at 0

  • All bars should be the same width


Pie chart

Pie Chart

  • Describe percentages of all the parts of population

  • Indicate the proportion

  • The 360o angle at the centre is apportioned to each item in the total in proportion of its magnitude .


Guidelines for pie charts

Guidelines for Pie Charts:

  • Give clear, complete title

  • Label all sections clearly

    • use a legend or key

  • Order by frequency

  • Start at top (12:00)

    • Move clockwise from start


Statistical tables and graphs

Fig.4 The pie chart


Statistical tables and graphs

10%

40%

15%

17%

18%

Fig.5 Percentages of the reasons for re-addiction (xx place,1996)


Statistical tables and graphs

A pie chart is good for making relative comparisons among pieces of a whole.


Percent bar chart

Percent Bar Chart

Compare frequencies of a category variable

  • Indicate the proportion


Statistical tables and graphs

Fig. 6 Mother’s education manner in group of drug addicts and group of controls. (xx place, 1996)


Line graph

Line Graph

Describe the changing of Y with X (time) -- tendency

Fig. 7 Incidence rates of stomach cancer in a city


General line graph

General Line Graph

  • Used for expressing a phenomenon changes with the time and condition, or one phenomenon changes with another phenomenon.

  • Its horizontal axis and vertical axis are all arithmetic rules.


Statistical tables and graphs

Fig.8 example of line graph


Semi logarithmic line graph

Semi-logarithmic Line Graph

  • Used for expressing the developing velocity (relative number) of a phenomenon changes with the time ,condition, or another phenomenon.

  • Unlike a general line graph, its horizontal axis is arithmetic rule and vertical axis is logarithmic rule.


Semi logarithmic line graph1

Semi-logarithmic Line Graph

Left: The absolute difference of mortality rates ~ Year

Right: The absolute difference of log (mortality rate)

Suitable line graphs in different situation


Histogram

Histogram

  • Describe a frequency distribution of continuous Quantitative Data

  • A histogram is a diagram in which:

    • The horizontal scale represents the value of the variable marked at interval boundaries.

    • The vertical scale represents the frequency or relative frequency in each interval


Statistical tables and graphs

Fig.9 Age distribution of first attack among 215 cases


Statistical tables and graphs

A histogram is the continuous data analogue of the bar chart.

  • It is a picture of the number of observations in each of the class intervals

  • The bars are adjacent or touching, which reflects the continuity of the data

  • Equal width intervals are strongly recommended

  • Area (width x height) of bar represents proportion

    in the interval


Statistical tables and graphs

Some guidelines for constructing histograms :

  • The graph title should be a complete description of the graph

  • Clearly label both the horizontal and vertical axes

    • label either endpoints or midpoints on horizontal axis

  • Include all intervals, even when “empty”

  • Break axes when necessary

  • Use equal class widths


Scatter diagram

Scatter Diagram

Describe the relationship between two numerical variables.

Is the relationship linear or non-linear?


Statistical tables and graphs

Fig 10 Relationship between temperature and deaths due to bronchitis and pneumonia.


Summary

Summary

  • A nice table can save a lot of words, show the fundamental characteristics and their relationship clearly.

  • Comparing to statistical tables, nice looking statistical plots are even more intuitive and understandable.

  • Contrarily, a poor organized table or a messy plot may sicken people.


Thank you

Thank you!


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