Biostat Week 3 ve 4

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Questions and Answers

What does the stem component of a value refer to in a stem and leaf plot?

The rightmost digit of the value
All digits except for the rightmost digit (correct)
Only the decimal part of the value
The entire number including the decimals

How should the leaves be arranged when constructing a stem and leaf plot?

In any random order without consideration for size
In ascending order, from smallest to largest for each stem (correct)
In descending order from the largest stem to the smallest
In pairs with their corresponding stems together

In a stem and leaf plot, where should the largest stem be positioned?

At the bottom of the plot only
In the middle of the plot for balance
At the top or bottom depending on preference (correct)
Only on the right side of the leaves

Which of the following correctly describes the purpose of a stem and leaf plot?

To summarize data without losing the original values (A) Signup and view all the answers

What is the primary advantage of using a stem and leaf plot, compared to a histogram?

It allows for easier comparison of exact data values (D) Signup and view all the answers

What is the primary purpose of organizing data into a frequency distribution?

To summarize and organize the data in a meaningful fashion (A) Signup and view all the answers

In a frequency distribution, what types of data are typically represented by categories and counts?

Ordinal and nominal data, structured in meaningful classes (C) Signup and view all the answers

What is the first step mentioned in the process of summarizing data?

Organizing the data in a meaningful fashion (C) Signup and view all the answers

During a survey aimed at assessing job satisfaction in dental hygiene, what type of data was likely collected?

Categorical responses regarding job satisfaction levels (B) Signup and view all the answers

Which statement best describes the role of frequency tables in analyzing sample data?

They allow for a structured representation of how often each category occurs. (D) Signup and view all the answers

What demographic trend does the line graph regarding Japanese women reflect from 1930 to 2000?

A decline in lifetime births per woman (B) Signup and view all the answers

Which event caused a notable break in the declining trend of birth rates in Japan?

A temporary increase in births between 1960 and 1970 (B) Signup and view all the answers

If the current trends continue, what is the expected outcome for the Japanese population?

It will continue to shrink (A) Signup and view all the answers

Which time period showed the most drastic drop in lifetime births per woman in Japan?

1950 to 1960 (D) Signup and view all the answers

What is indicated by the statement that the lifetime births per woman in Japan in 2000 is less than one-third of that in 1930?

A significant demographic shift (D) Signup and view all the answers

What type of data can be represented with a line graph according to the content?

Comparative data sets across different demographics (A) Signup and view all the answers

In the context of dental treatments, what was one of the categories mentioned regarding prosthodontic treatments?

Metal-ceramic fixed partial dentures (C) Signup and view all the answers

What is the primary purpose of the survey question regarding appointment length?

To assess quality of care improvement (D) Signup and view all the answers

Which of the following best describes what occurred to Japan's birth rate post-1980?

It dropped significantly below replacement level (A) Signup and view all the answers

How are the responses to the ordinal data typically categorized in the study?

By combining adjacent categories based on agreement levels (A) Signup and view all the answers

In the combined data, how many individuals responded with 'neutral'?

49 (A) Signup and view all the answers

What does the study suggest as a possible cause for root canal failure?

Persistence of bacteria in dentinal tubules (D) Signup and view all the answers

Which of the following is NOT a response option provided in the survey?

Completely agree (A) Signup and view all the answers

Which two response categories could be combined to simplify the frequency distribution?

Strongly disagree and disagree (A) Signup and view all the answers

What innovative methods are being introduced in endodontic therapy according to the study?

Intracanal laser irradiation and new materials (B) Signup and view all the answers

How many total responses were collected in the survey questionnaire regarding appointment length?

179 (A) Signup and view all the answers

What is the approximate number of intervals needed for a data set with 90 observations?

9 or 10 (C) Signup and view all the answers

How does the range of values in a data set affect the number of required intervals?

A larger range suggests a greater number of intervals. (D) Signup and view all the answers

What is the formula for determining the width of each interval in a frequency distribution?

Interval Width = Range of Data ÷ Number of Intervals (C) Signup and view all the answers

What should be the first step when constructing a frequency distribution?

Select the number of non-overlapping intervals. (B) Signup and view all the answers

Which of the following statements is true regarding the selection of non-overlapping intervals?

Non-overlapping intervals ensure accurate counting of observations. (B) Signup and view all the answers

In general, how many intervals should one aim for when dealing with a large data set?

10-20 intervals (A) Signup and view all the answers

What is indicated by the symbol ‘≅’ in the context of mathematical approximation?

Approximately equal to (D) Signup and view all the answers

If a data set comprises a small number of measurements, what should be the approach regarding intervals?

Have a few intervals to represent the limited data. (B) Signup and view all the answers

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Study Notes

Line Graphs

A line graph with an x-axis representing time allows for comparison of quantity changes over a defined period.
An example of this is the number of lifetime births per Japanese woman.
The rate of births has decreased steadily since 1930 except for a break between 1960 and 1970.
Japan's birth rate is lower than the replacement level of 1.7-1.8.
The birth rate has been below 1.7-1.8 since 1980 resulting in a shrinking population.
More than one group's data can be represented in the same line graph which allows for comparisons.

Stem and Leaf Plots

Separate each value into a stem and a leaf.
- The stem consists of all digits except for the rightmost digit, which is the leaf.
- For example, 76.8 has a stem of 76 and a leaf of 8.
The smallest stem value is placed at the top of the plot with the largest stem at the bottom.
The leaves are arranged in ascending order to the right of the stem's vertical line.

Frequency Distribution

Summarize data by organizing it in a frequency table.
Shows how many times each data point appears in the data set.
The first step to summarizing data is to create a frequency distribution, which is a table showing how often each data point occurs in a set.
Frequency distributions are used for nominal and ordinal data.
Example 1: Table F1 displays prosthodontic services provided during 1991–1998.
Example 2A: Table F2 displays results of a survey on job satisfaction which shows responses to a question related to appointment length.
Example 3: Table F3 illustrates the effect of disinfection by laser irradiation on the bacteria in dentinal tubules.
Frequency distributions are useful in visualizing the data and identifying trends.
A frequency distribution for nominal or ordinal data shows the number of observations in each category.
- For ordinal data categories such as strongly disagree to strongly agree, they can be combined.

Frequency Distributions (continued)

Use 10-20 intervals in a frequency distribution.
The number of intervals should be approximately equal to the square root of the number of observations (√n).
The interval width is calculated by dividing the range by the number of intervals.
Table F4 shows the number of observations and range of values for the bacterial colony data.
The frequency distribution is constructed by:
- Selecting the number of non-overlapping intervals
- Choosing a starting point for the lowest class limit (which can be the smallest value or a convenient number less than the smallest observed value)
- Determining the upper and lower limits for each interval
- Counting the number of observations in each interval.

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