# Essay: Aspects and features of research ### Essay details:

• Subject area(s): Science essays
• Number of words: 396
• File format: PDF
• Overall rating: 0 out of 5 based on 0 reviews.

### 500 word text preview of this essay:

The full version of this essay has 396 words and is available to download in PDF format above.

This essay explains what various research terms mean, and provides examples for each.
A random variable is a set of possible numerical outcome or value from a random experiment that is selected by chance. The outcome is a function from a sample space that is mapped into real numbers. It can be classified into: continuous random variable, which takes an infinite number of possible outcomes, or discrete which is countable.
Example:
Continuous: Experimenter wish to estimate the height of NBA basketball players. Measuring the height of each of the player rather inefficient, hence experimenter choose 30 players randomly from a set of all NBA players (sample space). Each basketball player in NBA has an equal chance of being selected. Thus each player selected for the sample is said to be a random variable. And height measurement can be anywhere between zero to infinity, hence continuous.
Discrete: number of heads when tossing a coin twice. Possible outcome or the sample space are HH, HT,TH,TT. Translated into the real line the possible number of heads, are 0,1 and 2.
Random sample is a subset of units or subjects from a population, where each unit in the population has an equal chance of being selected.
Example:
In a company consists of 300 employees (population), 30 people are selected randomly. The 30 people selected are called a random sample because they are selected by chance, each employee has an equal chance of being selected.
Mgf stands for moment generation function of x is denoted by M_x (t), exists if there is a positive number h such that the above summation exists and is finite for ‘h< t < h. By definition we can write mgf of X as:
Let X be a random variable with probability mass function f(x) and an element of S. Then:
M_x (t)=E(e^tx )=’_(x’S)”e^tx P(X=x)’ , if x is discrete
M_x (t)=E(e^tx )=’_(-‘)^”’e^tx f(x) dx’ , if x is continuous
Also, by theorem if X has mgf M_x (t) then
EX^n=’M_x’^((n) ) (0),
Where
‘M_x’^((n) ) (0)=d^n/’dt’^n M_x (t)|_0
Is the nth moment which can be found by deriving M_x(t) nth times and evaluating it at t=0.
Example:
Let x be distributed exponentially, hence the probably distribution function of x is
f(x)=1/?? e^((-x)/??) 0<x<‘ , ??>0
Obtaining the mgf we take:
E[e^tx ]=’_0^”'(e^tx 1/?? e^((-x)/??) [email protected] )
=1/(1-??t), t<1/??
Is the moment generating function of exponential distribution.
Observational study is a study where the investigators observe subjects and measure variables of interest without applying any treatments to the subjects.
Example:
A research study comparing the risk of developing heart disease between people who exercise regularly (at least three times a week for an hour each session) and people who do not exercise regularly. Experimenter only observe without altering any variable in the experiment or the environment.
Experimental study is a study where the investigators apply treatments to the experimental units and then measure the effect of the treatments on the variable of interest.
Example:
A research study comparing weight loss …

This essay was submitted to us by a student in order to help you with your studies.

If you use part of this page in your own work, you need to provide a citation, as follows:

Essay Sauce, Aspects and features of research. Available from:<https://www.essaysauce.com/science-essays/essay-aspects-and-features-of-research/> [Accessed 19-07-19].

### Review this essay:

Please note that the above text is only a preview of this essay. The full essay has 396 words and can be downloaded free in PDF format, using the link above.