# week 2 Flashcards

What is a variable?

any characteristic that differs among individuals

What is Categorical variable?

Categorical variable describe membership to a group are qualitative not quantitative. characteristics and do not have a magnitude orn a numerical scale.

What is a numerical data?

are quantitative measurements that have magnitude on a numerical scale.

is age at death numerical or categorical?

numerical

are size classes numerical or categorical?

categorical

is number of mates numerical or categorical?

numerical

What is an explanatory variable?

The variable that predicts or affects the response variable. Is the one manipulated by the researcher.

What is the response variable?

measured effect of the treatment

What are descriptive statistics or summary statistics?

quantities that capture important features of frequency distributions(Standard deviation, mean)

What is the most important descriptive statistics for categorical variables?

the proportion

What do the most important descriptive statistics do?

measure the:

location

spread

of a frequency distribution

What is the sample mean?

The average of the measurements in the sample, the sum of all observations divided by the number of observations(n).

What does the standard deviation measure?

the spread of a distribution. It indicates just how different measurements typically are from the mean.

What is the mean?

the middle measurement of a set of observations

What is the interquartile range?

The difference between the third and first quartiles of the data. It is the span of the middle 50% of the data.