24 Questions
What is the shape of a curve when the data concentrates at both ends?
U-shaped
What does positive skewness indicate?
Most unusual values are on the high end of the range
What is the purpose of a line graph in statistics?
To show the dose-response curves
What is the main purpose of a pie diagram?
To show the split of a total into constituent parts
What is the advantage of summarizing large data sets using few numbers?
It makes the data more manageable
What does the angle of each sector in a pie diagram represent?
The proportion of each category
What is the term for the amount of spread in a distribution?
Dispersion
What do two curves with the same shape but different positions on the x-axis have?
Different locations
What is a characteristic of discrete numerical data?
Values are counted and are usually integers.
What is the purpose of a control group in an experiment?
To provide a baseline for comparison.
Which step in the experimental design process is often overlooked?
Design of experiments.
What is the benefit of a good experimental design?
It gives accurate and reliable results from the smallest number of subjects.
What is an example of continuous numerical data?
The blood pressure of a patient.
What is the purpose of statistical analysis in an experiment?
To analyze and interpret the data collected.
What is a common error in statistical analysis?
Not using statistical analysis in the design of the experiment.
Which of the following is a characteristic of good experimental design?
It minimizes the difficulties associated with variability.
What is the probability of a tablet being rejected if the batch size is 10,000?
0.1336
What is the purpose of statistical analysis in a pharmacological study?
To find out if the effect produced by the compound is genuine and not due to chance
What is the level of significance that indicates the probability that the difference is significant is 5%?
P < 0.05
What is the name of the test used to compare the means of two or more groups?
Analysis of Variance (ANOVA) test
What is the calculation for Z1 in the problem?
(4.7 - 5) / 0.2
What is the name of the test used to compare the means of two groups, where the data is paired?
Student's t-test
What is the area of Z1 in the problem?
0.0668
What is the purpose of the test of significance?
To prove if the difference between the means is true or due to chance
Study Notes
Types of Frequency Curves
- Bell-shaped curves: can be symmetrical or asymmetrical, and may be U-shaped when data concentrates at both ends
- Skewed curves: frequency curve extends in one direction more than the other, with skewness to the right (positively skewed) or left (negatively skewed)
Characteristics of Frequency Curves
- Location: two curves may be of the same shape, but occupy different positions on the x-axis
- Dispersion: two curves may have the same shape, but one may contain x-values extending over a wider range on the x-axis than the other
Graphs
- Line graphs: used for dose-response curves and when the effect is measured at different times
- Pie diagrams: show the split of a total into constituent parts, with the angle of each sector proportional to the relative frequency
Data Types
- Numerical (metric) data: have true numbers with an average and standard deviation, can be discrete or continuous
- Discrete data: possibilities are limited (finite), values are counted, usually integers
- Continuous data: possibilities are unlimited (infinite), values are measured, can be any number
Steps of Experiments
- Design of experiments
- Collection of data
- Presentation of collected data
- Analysis of data
- Interpretation of analyzed data
Experimental Design
- Principal application of statistics is not only in the analysis of final data but also in the designing of the experiment
- Good designs save time, give accurate and reliable results, and minimize difficulties associated with variability
- Experimental design involves dividing animals or humans into groups exposed to identical conditions
Statistical Analysis
- Primary aim is to find out whether the effect produced by the compound under study is genuine and not due to chance
- Tests of significance include:
- Student's t-test (for graded data)
- Chi-square test (for all or none data)
- Analysis of variance (ANOVA) test (for more than two groups)
Levels of Significance
- Most common levels of significance are:
- P < 0.05 (5% level)
- P < 0.01 (1% level)
- P < 0.001 (0.1% level)
- Level of significance indicates the probability that the difference is significant
This quiz covers the characteristics of different types of frequency curves, including bell-shaped and U-shaped curves, as well as skewed curves.
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