SOC 390 Final Exam

The reasoning behind using N- 1 rather than N in the denominator of the standard deviation

(n−1) is a smaller number than (n). When you divide by a smaller number you get a larger number. Therefore when you divide by (n−1) the sample variance will work out to be a larger number.

13.Understand the three primary characteristics of the normal curve

1. The mean, median, and mode are all equal. 2. The total area under the curve is 1 3. The curve is symmetric at the center

16.Understand z-scores and what they are used for

A z score is used to calculate the probability something will occur within the normal distribution.

12.Know why we care about probability in statistics

Because data used in statistical analyses often involves some amount of "chance" or random variation

1.What are descriptive and inferential statistics

Descriptive statistics summarize the characteristics of a data set. Inferential statistics allow you to test a hypothesis or assess whether your data is generalizable to the broader population.

Correlation does not equal causation!

Loneliness does not cause depression and depression does not cause loneliness just because it has a high correlation. We do not know which causes which X->Y OR Y->X

21. Understand why the mean is considered an unbiased estimator

Mean is unbiased as it is the average of the entire data set

6.When is it appropriate to use each measure of central tendency

Mean is used when there are no major outliers, as mean can be affected by outliers. Median is the preferred measure of central tendency when there are a few extreme scores in the distribution of the data. Mode is the preferred measure when data are measured in a nominal ( and even sometimes ordinal) scale.

3.The three measures of central tendency and what they are conceptually

Mean, Median, and Mode. Mean is the average of the data, median is the middle of a data set, and mode is the most occurring numbers in a data set.

8.The three measures of variability and what they are conceptually

Range, Standard deviation, and variance. Range measures the spread of your data from high to low. Standard deviation measures the spread of the data about the mean value. Variance is a measure of how data points differ from the mean.

9.The types of variability estimates that are the most and least precise

Standard deviation,then variance, then range

14.Know what the area under the curve is for the normal distribution

Tells you the probability of variables taking on a range of values

5.The characteristics of mean and median (HINT: pay attention to how outliers influence these measures)

The mean is suitable only when the distribution is symmetric while the median is appropriate when the distribution is skewed.

4.The difference between a population distribution and a sample distribution.

The population distribution gives the values of the variable for all the individuals in the population. The distribution of sample data shows the values of the variable for all the individuals in the sample

2.The concept of an average

The sum of the values of a group of numbers divided by the amount of numbers in the group.

7. What is variability

lack of a fixed pattern/lack of consistency

11.Know if the mean and standard deviation are influenced by outliers

yes