Presenting Data in Charts and Tables Hartanto, SIP, MA Ilmu Hubungan Internasional Fakultas Ilmu Sosial dan Ekonomi Universitas Respati Yogyakarta 2012

In an information-overloaded world, you need to present information effectively. You can present categorical and numerical data efficiently using charts and tables. Studying this class can help you learn to select and develop charts and tables for each type of data.

Presenting Categorical Variables

Steps to Present Categorycal Variables  Sort variable values according to the categories of the variable.  Place the count, amount, or percentage (part of the whole) of each category into a summary table or into one of several types of charts.

The Summary Table  Concept  A two-column table in which category names are listed in the first column and the count, amount, or percentage of values are listed in a second column. Sometimes, additional columns present the same data in more than one way (for example, as counts and percentages).

 Interpretation  Summary tables enable you to see the big picture about a set of data. In this example, you can conclude that more than half the people pay by check and almost 75% either pay by check or by electronic/online forms of payment.

Question Example Survey Penggunaan Alat Transportasi oleh Mahasiswa untuk Pergi Ke Kampus (N=100) NoJenis Alat TransportasiJumlah 1Mobil5 2Sepeda Motor35 3Sepeda27 4Angkutan Umum23 5Lain-Lain10 Jumlah100 Buatlah Summary Table dari data diatas?

The Bar Chart (Diagram Batang)  Concept  A chart containing rectangles (“bars”) in which the length of each bar represents the count, amount, or percentage of responses of one category.

 Interpretation  A bar chart is better than a summary table at making the point that the category “pay by check” is the single largest category for this example. For most people, scanning a bar chart is easier than scanning a column of numbers in which the numbers are unordered, as they are in the bill payment summary table.

Question Example Survey Penggunaan Alat Transportasi oleh Mahasiswa untuk Pergi Ke Kampus (N=100) NoJenis Alat TransportasiJumlah 1Mobil5 2Sepeda Motor35 3Sepeda27 4Angkutan Umum23 5Lain-Lain10 Jumlah100 Buatlah Bar Chart dari data diatas?

Steps to Create Bar Chart  Buat garis absis (x) dan ordinat (y).  Tentukan judul dari absis (x) dan ordinat (y) sesuai dengan tabel distribusi frekuensi yang ada.  Tentukan penskalaannya berdasarkan batas riil (nyata).  Buat kota persegi empat pada absisnya dan disesuaikan dengan frekuensi pada ordinatnya.

The Pie Chart (Diagram Bagian Bulat)  Concept  A circle chart in which wedge- shaped areas—pie slices—represent the count, amount, or percentage of each category and the entire circle (“pie”) represents the total.

 Interpretation  The pie chart enables you to see each category’s portion of the whole. You can see that most of the adults pay their monthly bills by check or electronic/online, a small percentage pay with cash, and that hardly anyone paid using another form of payment or did not know how they paid.

Question Example Survey Penggunaan Alat Transportasi oleh Mahasiswa untuk Pergi Ke Kampus (N=100) NoJenis Alat TransportasiJumlah 1Mobil5 2Sepeda Motor35 3Sepeda27 4Angkutan Umum23 5Lain-Lain10 Jumlah100 Buatlah Pie Chart dari data diatas?

The Pareto Chart  Concept  A special type of bar chart that presents the counts, amounts, or percentages of each category in descending order left to right, and also contains a superimposed plotted line that represents a running cumulative percentage.

Question Example Survey Penggunaan Alat Transportasi oleh Mahasiswa untuk Pergi Ke Kampus (N=100) NoJenis Alat TransportasiJumlah 1Mobil5 2Sepeda Motor35 3Sepeda27 4Angkutan Umum23 5Lain-Lain10 Jumlah100 Buatlah Pareto Chart dari data diatas?

Presenting Numerical Variables

 You present numerical variables either in tables or charts.  To create a table you first establish groups that represent separate ranges of values and then place each value into the appropriate group.  To create a chart, you use the groups from the table.

The Frequency and Percentage Distribution  Concept  A table of grouped numerical data that contains the names of each group in the first column, the counts (frequencies) of each group in the second column, and the percentages of each group in the third column. This table can also appear as a two-column table that shows either the frequencies or the percentages.  Interpretation  Frequency and percentage distributions enable you to quickly determine differences among the many groups of values.

Contoh: Hasil UAS Pengantar Ilmu Hubungan Internasional FISE RESPATI NilaiFrekuensiPersentase % % % % % Jumlah (N)100100%

Histogram  Concept  A special bar chart for grouped numerical data in which the frequencies or percentages in each group of numerical data are represented as individual bars on the vertical Y axis and the variable is plotted on the horizontal X axis. In a histogram, in contrast to a bar chart of categorical data, no gaps exist between adjacent bars.  Interpretation  Histograms reveal the overall shape of the frequencies in the groups. Histograms are considered symmetric if each side of the chart is an approximate mirror image of the other side.

Contoh Soal: Hasil UAS Pengantar Ilmu Hubungan Internasional FISE RESPATI. Buatlah Histogram dari data Dibawah ini. NilaiFrekuensiPersentase % % % % % Jumlah (N)100100%

The Time Series Plot  Concept  A chart in which each point represents the value of a numerical variable at a specific time. By convention, the X axis (the horizontal axis) always represents units of time, and the Y axis (the vertical axis) always represents units of the variable.

Misusing Charts

Concept  All the charts presented in this class enhance our understanding of the data being presented. Such graphs are considered “good” graphs.  Unfortunately, many charts that you encounter in the mass media or in formal reports are “bad” charts that misuse the techniques discussed in this class.  Bad charts mislead, unnecessarily complicate things, or are just plain incorrect and should always be avoided.

Interpretation  Using pictorial symbols, instead of bars or pies, always obscures the data and can create a false impression in the mind of the reader, especially if the pictorial symbols are representations of three- dimensional objects.

In Example 1, the wine glass symbol fails to communicate that the 1997 data (6.77 million gallons) is almost twice the 1995 data (3.67 million gallons), nor does it accurately reflect that the 1992 data (2.25 million gallons) is a bit more than twice the 1.04 million gallons for 1989.

Example 2 combines the inaccuracy of using a picture (grape vine) instead of a standard shape with the error of having unlabeled and improperly scaled axes. A missing X axis prevents the reader from immediately seeing that the 1997–1998 value is misplaced. By the scale of the graph, that data point should be closer to the rest of the data. A missing Y axis prevents the reader from getting a better sense of the rate of change in land planted through the years. Other problems also exist. Can you spot at least one more? (Hint: Compare the 1949–1950 data to the 1969–1970 data.)