Question

What is descriptive statistics?

What is inferential statistics?

Why do we care about the level of measurement of a variable?

Why do we use n-1 rather than n in calculating sample variance?

What are confounding variables, and what effect do they have on assessing cause-and-effect relationships?

When would you prefer median to mean as a measure of central tendency?

Why don’t we just sum the deviations from the mean to measure dispersion of a variable?

When is it legitimate to use the empirical rule?

How would you go about identifying outliers in your data?

What would you do if you found an outlier?

What is accomplished by randomization in an experiment?

Describe the scatterplot and regression line that would correspond to a correlation coefficient of 0.9.

What is r 2 and what is the logic behind the measure?

What do y and yˆ represent in regression analysis?

What is meant by sampling bias, nonresponse bias, and response bias?

what is a ‘double-blind’ study?

What is the placebo effect?

Answer 1

(1) Descriptive statistics describe the basic features of data in a study, as given by 4 types:

(i) Measures of Frequency

(ii) Meansures of Central Tendency

(iii) Measures of Dispersion

(iv) Measures of position

(2) Inferential statistics uses a random sample of data taken from a population to make inferences about the population. With inferential statistics, we make generisation from sample statistics regarding the corresponding population parameters.

(3) Level of measurement of a variable gives the scale of measurement of a variable describing the nature of information within the values assigned to variables with 4 levels of measurement:
(i) Nominal

(ii) ordinal

(iii) interval

(iv) ratio

(4)

We use n -1 rather than n in calculating standard variance in order to get unbiased estimate of the population variance.

By Theorm:

gives the biased estimate of population variance .

With Bessel's correction:

gives unbiased estimate of population variance .

AS PER DIRECTIONS FOR ANSWERING, FIRST 4 QUESTIONS ARE ANSWERED.