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31 Data Analysis Questions And Answers

1⟩ List the properties which are satisfied by the normal distributions?

All normal distributions satisfy the following properties:

★ Approximately 68% of the observations fall within 1 standard deviation of the mean

★ Approximately 95% of the observations fall within 2 standard deviations of the mean

★ The mean, median and mode of the data are nearly all equal


2⟩ Tell me about median?

The median of a set of numbers is the number that is exactly half way between the largest and smallest number, when the numbers are arranged from smallest to largest.


3⟩ Please tell me what is a box plot?

A box plot graphically displays groups of numerical data through their five-number summaries: the smallest observation (sample minimum), lower quartile (Q1), median (M), upper quartile (Q2) and largest observation (sample maximum).

The box plot is often called a "whisker" plot because "whiskers" extend outward from the boxes to the least and greatest values.


6⟩ What is average?

The average or the arithmetic mean is defined as the sum of all measurements divided by the number of observations. For example, the average of the numbers 10, 12 and 22 is 14.6 because 10+12+22=44 and there are three observations, so 44 divided by three is 14.6. When there are only numbers involved, an average problem is quite simple.


7⟩ What is data analysis?

Data analysis is the process of systematically applying statistical and/or logical techniques to describe and illustrate, condense and recap and evaluate data.


13⟩ Explain the difference between association, causation and confounding?

One of the most important issues in interpreting research findings is understanding how outcomes relate to the intervention that is being evaluated. This involves making the distinction between association and causation and the role that can be played by confounding factors in skewing the evidence.


14⟩ Define confounding with example?

To rule out that a relationship between two events has been distorted by other, external factors, it is necessary to control for confounding. Confounding factors may actually be the reason we see particular outcomes, which may have nothing to do with what is being measured.

To rule out confounding, additional information must be gathered and analyzed. This includes any information that can possibly influence outcomes.


When mounting a campaign against alcohol-impaired driving, it is important to know whether other interventions aimed at road traffic safety are being undertaken at the same time. Similarly, if the campaign coincides with tighter regulations around BAC limits and with increased enforcement and roadside testing by police, it would be difficult to say whether any drop in the rate of drunk-driving crashes was attributable to the campaign or to these other measures.


16⟩ Define causation with example?

A causal relationship exists when one event (cause) is necessary for a second event (effect) to occur. The order in which the two occur is also critical.


★ For intoxication to occur, there must be heavy drinking, which precedes intoxication.

★ Determining cause and effect is an important function of evaluation, but it is also a major challenge.

Causation can be complex:

★ Some causes may be necessary for an effect to be observed, but may not be sufficient; other factors may also be needed.

★ While one cause may result in a particular outcome, other causes may have the same effect.

Being able to correctly attribute causation is critical, particularly when conducting an evaluation and interpreting the findings.


18⟩ What is set in data analysis?

A set is a collection of distinct objects that have a specific property.

For example, the set of all digits greater than 5 includes the numbers 6, 7, 8 and 9.


19⟩ Define normal distribution in data analysis?

The normal distribution is a pattern for the distribution of data which follows a bell-shaped curve. The normal distribution is called normal because the data points are concentrated in the center near the mean. The data does not usually contain extreme values and the probability of deviations of the data points from the mean are (nearly) identical in either direction.


20⟩ Define association in data analysis with example?

An association exists when one event is more likely to occur because another event has taken place. However, although the two events may be associated. One does not necessarily cause the other. The second event can still occur independently of the first.


Some research supports an association between certain patterns of drinking and the incidence of violence. However, even though harmful drinking and violent behavior may co-occur, there is no evidence showing that it is drinking that causes violence.