Types of Frequency Curves

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Questions and Answers

What is the shape of a curve when the data concentrates at both ends?

Skewed

U-shaped (correct)

Asymmetrical

Bell-shaped

What does positive skewness indicate?

The data is asymmetric

Most unusual values are on the high end of the range (correct)

The data is normally distributed

Most unusual values are on the low end of the range

What is the purpose of a line graph in statistics?

To show the pie chart

To show the correlation between two variables

To compare the distribution of two variables

To show the dose-response curves (correct)

What is the main purpose of a pie diagram?

To show the split of a total into constituent parts Signup and view all the answers

What is the advantage of summarizing large data sets using few numbers?

It makes the data more manageable Signup and view all the answers

What does the angle of each sector in a pie diagram represent?

The proportion of each category Signup and view all the answers

What is the term for the amount of spread in a distribution?

Dispersion Signup and view all the answers

What do two curves with the same shape but different positions on the x-axis have?

Different locations Signup and view all the answers

What is a characteristic of discrete numerical data?

Values are counted and are usually integers. Signup and view all the answers

What is the purpose of a control group in an experiment?

To provide a baseline for comparison. Signup and view all the answers

Which step in the experimental design process is often overlooked?

Design of experiments. Signup and view all the answers

What is the benefit of a good experimental design?

It gives accurate and reliable results from the smallest number of subjects. Signup and view all the answers

What is an example of continuous numerical data?

The blood pressure of a patient. Signup and view all the answers

What is the purpose of statistical analysis in an experiment?

To analyze and interpret the data collected. Signup and view all the answers

What is a common error in statistical analysis?

Not using statistical analysis in the design of the experiment. Signup and view all the answers

Which of the following is a characteristic of good experimental design?

It minimizes the difficulties associated with variability. Signup and view all the answers

What is the probability of a tablet being rejected if the batch size is 10,000?

0.1336 Signup and view all the answers

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 Signup and view all the answers

What is the level of significance that indicates the probability that the difference is significant is 5%?

P < 0.05 Signup and view all the answers

What is the name of the test used to compare the means of two or more groups?

Analysis of Variance (ANOVA) test Signup and view all the answers

What is the calculation for Z1 in the problem?

(4.7 - 5) / 0.2 Signup and view all the answers

What is the name of the test used to compare the means of two groups, where the data is paired?

Student's t-test Signup and view all the answers

What is the area of Z1 in the problem?

0.0668 Signup and view all the answers

What is the purpose of the test of significance?

To prove if the difference between the means is true or due to chance Signup and view all the answers

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