1. welcome...

Art of Stat Handout 2020-21 Handout 01 Introduction

… Art of Stat/Art of Stat Handout Fall 2020 – Introduction.docx of 12

Introduction to Art of Stat 2020-21

Introduction

www.artofstat.com

Table of Contents

Page 1. Welcome ……………………………………………….…..……………………………………..

2

2. Illustration: Describe a Sample of Categorical Data……...…………………….……………

4

3. Illustration: Describe a Sample of Continuous Data …….…………………………………..

11



1. Welcome www.artofstat.com is a nice “go to” for the newcomer to biostatistics who might not be quite ready to jump into a statistical software package, much less doing one’s own programming! This site was developed and continues to be maintained by authors Agresti A, Franklin C, and Klingenberg B who authored an excellent introductory statistics text:

Agresti A, Franklin C, and Klingenberg B. Statistics: The Art and Science of Learning From Data, 4th Edition 2017 Pearson ISBN 13: 9780321997838

How to Launch. From your favorite browser, launch www.artofstat.com From the welcome page, at left, click anywhere inside the large icon titled, Web Apps



Look around Clicking on Web Apps brings you to a directory of several apps. They are organized into categories and many are useful in BIOSTATS 540:

- Good for producing summary statistics and some basic graphs (BIOSTATS 540 Units 1 and 2)

- Good for simple linear regression (BIOSTATS 540 Unit 12)

- Good for confidence intervals and p-values (BIOSTATS 540 Units 8, 9, and 10)

- Exactly. (BIOSTATS 540 Units 1, 5, and 7)

- Exactly. (BIOSTATS 540 Units 8 and 9

- Exactly. (BIOSTATS 540 Units 8 and 10)

- Good for the Fisher Exact Test. (BIOSTATS 540 Unit 11)



2. Illustration Describe a Sample of Categorical Data

Example – Question #1 of the Unit 2 (Data Visualization) Homework Data Entry Method: Direct entry of frequency table (“by hand”) The World Health Organization (WHO) records the annual number of confirmed cases of human Avian Influenza A/(H5N1). Following are a subset of their data: Year: 2003 2004 2005 2006 2007 2008 # cases: 4 32 43 79 59 26 In this illustration, there are two (2) variables.

year: This is a nominal variable with 6 levels = 2003, 2004, 2005, 2006, 2007, 2008 cases: This is the associated number of confirmed cases of influenza in that year)

GOAL: Produce a description of the distribution of cases over time (year). The description is to include a frequency/relative frequency table and a bar graph. Step 1 – Launch Art of Stat www.artofstat.com > Web Apps > EXPLORE CATEGORICAL DATA You should see:

Key: Art of Stat is showing you the frequency/relative frequency table and associated bar graph for one of its own data sets. You can enter your own.



Step 2 – Replace the dataset shown with your own data. At the upper left, from the dialogue boxes and drop-down menus, make the following selections/inputs: Enter Data: Frequency Table Number of Categories: 6 Name of Variable: Year You should now see an empty Art of Stat analysis, waiting for you to enter your data

After entering your data, Art of Stat returns the following



Have some fun with the options at left



Example – Unit 1 (Summarizing Data), page 40 Data Entry Method: From Excel – Paste of individual observations Recall. This is a study of n=25 consecutive patients entering the general medical/surgical intensive care unit at a large urban hospital. One of the variables measured was ICU_TYPE, which is a nominal variable indicating the type of ICU admission. Recall how it was coded:

1 = medical 2 = surgical 3 = cardiac 4 = other

These data have been put into an excel file for you called icu_540.xlsx. In this excel file ICU_TYPE is stored in a column labeled icu_type

GOAL: Produce a description of the distribution of the types of ICU admissions in this sample.



Step 1 – In Excel Open icu_540.xlsx. Minimize Excel. Do NOT exit Excel. Step 2 – Launch Art of Stat www.artofstat.com > Web Apps > EXPLORE CATEGORICAL DATA Step 3 – Replace the dataset shown with your own data. At the upper left, from the dialogue boxes and drop-down menus, make the following selections/inputs: Enter Data: Individual Observations Name of Variable:: Type of ICU Enter categorical observations, separated by a space. Or, simply copy and paste values from a column in your spreadsheet: See Step 4 below …

Step 4 – COPY/PASTE from Excel into Art of Stat In this illustration we copy/paste the column of Excel data corresponding to icu_type

No, no, no!!!!! This is not what we wanted!!!!! … The horizontal shows the codings (1, 2, 3, 4) instead of their names. Worse, they’re not in the right order.



Step 5 – In Excel, create a column of individual outcomes stored as names __ Copy the column of icu_type into a new “sheet”. __ Select the entire column. Then FORMAT CELLS > TEXT __ Position cursor in cell A:1 __ Use EDIT > FIND > REPLACE ALL to convert 1 à medical __ Use EDIT > FIND > REPLACE ALL to convert 2 à surgical __ Use EDIT > FIND > REPLACE ALL to convert 3 à cardiac __ Use EDIT > FIND > REPLACE ALL to convert 4 à other Your new excel sheet should look like the following:



Step 6 – COPY/PASTE your newly created data from Excel into Art of Stat Be sure to begin with row 2!!! You don’t want to copy/paste the variable name in row 1 That’s better

Again, have some fun with the options at left



3. Illustration

Describe a Sample of Continuous Data Example – Unit 1 (Summarizing Data), page 40 Data Entry Method: From Excel – Paste of individual observations Consider again the same study of n=25 consecutive patients entering the general medical/surgical intensive care unit at a large urban hospital. There is one continuous variable in this dataset: age. Goal: A description of the distribution of age Step 1 – In Excel Open icu_540.xlsx. Minimize Excel. Do NOT exit Excel. Step 2 – Launch Art of Stat www.artofstat.com > Web Apps > EXPLORE QUANTITATIVE DATA Step 3 – Replace the dataset shown with your own data. At the upper left, from the dialogue boxes and drop-down menus, make the following selections/inputs: Enter Data: Your Own Do you have: Individual Observations (How nice! There is also an option for entering grouped data here!) Name of Variable: Age You should see the following at this point.



Step 4 – COPY/PASTE from Excel into Art of Stat Now we copy/paste the column of Excel data corresponding to age Not bad!

Playing around with options at left, I now have the following. You might make different selections; o for it!

1. welcome...

Documents