AD RESEARCH FINAL: Descriptive Statistics

Regression Analysis

Most common method for determining correlation. Regression and correlation are used to determine whether the relationship between sets of variables is significant, that is, unlikely to occur by chance.

Tool that enables us to make inferences from samples to populations

Normal Curve

Basic Correlation Statistics

Numerical expressions of the degree to which two variables change in relation with one another (covary) are called measures of association or correlation. Typically, the variable presumed to be antecedent is designated "X" and the criterion "Y". Correlation is valuable because it is the simplest statistic that can be used to assess the relationship between two interval or ratio variables

What kind of technique is a thematic apperception test?

Projective Technique

Central Limit Theorem

Provides assurance that any random sample statistic comes from a population of statistics that form a normal curve around the true population parameter.

What is the probability in the area below a normal curve called

Rejection of the null hypothesis

What has to be at least at the ordinal level for the median to be a meaningful measure of central tendency?

A distribution of numbers

Rule for Percentaging Calculations

Always calculate percentages in the direction of the causal factor (antecedent/x/independent) and across the effect (criterion/y/dependent) factor.

Where does the independent variable go in a contingency table?

At the top of a cross tabulation of contingency table

Curves and their shapes

Bell-shaped Positive Skew Negative Skew

"What can we do with that data using what kind of analyses that help us address the original research problem at greater depth?"

Bivariate

use a scatterplot

Bivariate

Means that two or more sets of variables are related to one another at the interval or rational level

Correlation

What is another form of determining correlation?

Significance

Inferential Statistics

Study a group of data and inferring the sample projects onto the larger population - More powerful than descriptive - Process of statistical inference

Cross Tabulation

Technique for studying the relationships between variables. Simplest technique for analyzing nominal variables in bivariate ways

The arithmetic average. The most power, but comes at a price.

The Mean

The midpoint of a distribution

The Median

The score or scores occurring most frequently

The Mode

Confidence Level

The level of statistical confidence that is built into the sample. Commonly in advertising and public relations research, we want to be confident that our results are right maybe 90 percent of the time. They tell us how likely our aim is to actually take place.

Purpose of research and methods

The main purpose for summary and descriptive methods of quantitative analysis are to reduce data and to enable us to see patterns and trends. You run the stats. If you find something important, you highlight it in the report. You always start with univariate statistics and analyses. Then you move on to whatever bivariate analyses will reveal something important about the research problem.

Statistical Inference

The process of estimating parameters (characteristics of a population) from statistics (characteristic of a sample). It's almost entirely necessary because we typically study samples instead of populations.

All projective techniques share what element in common?

They are all based on the projective hypothesis

True or False? All quantitative data, regardless of level of measurement, can be analyzed with frequency distribution tables, proportions, percentages and ratios

True

True or False? If you want to know how well the mean represents a distribution of numbers, you should also look at the standard deviation

True

True or False? Inferential statistics are more powerful than descriptive statistics.

True

True or False? Measure of dispersion can be used to reveal the "shape" of a distribution of scores or numbers

True

True or False? The chi-square statistic and test for significance is typically used with data measured at the nominal level.

True

True or False? The term that's used to describe whether a distribution's curve is tall and peaked or short and flat is called "kurtosis"

True

True or False? Unlike the mode and the median, the mean takes into account all the values in a distribution making it especially sensitive to the effects of extreme scores

True

True or False? You could reduce data using a frequency distribution table.

True

True or False? A distribution of numbers has to be at least ordinal level for the median to be a meaningful measure of central tendency?

True

True or False? Frequency distributions are one method for presenting data in descriptive statistical analysis

True

True or false? The square root of the variance of a distribution of numbers is the standard deviation

True

Once you've collected your data, you begin with univariate analysis. One good way to begin is by looking at the items you have that measure related concepts and variables.

Univariate

Inferential Statistics are used for?

Used to make estimates of how likely it is these statistics represent the population

The T-Test

Used to test for significance between two means. The independent or antecedent variable is nominal and the dependent or criterion variable must be interval or ratio.

ANOVA

Used to test for significant differences among three or more means. Type of regression analysis.

Pearson's r

Varies between -1.00 and +1.00. Values closer to one contain greater significance. Pearson's r can be tested for significance. Relationships can be "spurious". Most researchers use adjectives such as "moderate" to "high" to describe the strength of correlations, but it depends on the nature of the phenomenon under study. "R" value Indicates the strength of a linear relationship

interval level of measurement

linear scale of measurement in which the distance or interval btw all integers along the scale is equal. reported as frequencies and percentages PLUS mean scores.

nominal level of measure

lowest level of measurement, data is placed into categories or classes without any order, value or structure.

- Used with interval and ratio - Average - Most powerful

mean

The sum of all scores in a distribution of numbers, divided by the number of scores is the definition of _____

mean

ordinal level of measure

measures and defines attributes and characteristics in an ordered sequence. ranks responses from the smallest to largest, best to worst and first to last

-used with interval and ratio - used with midpoint distribution

median

- Used only with nominal level of measurement (weakest)

mode

Probability level is usually expressed by a lowercase _____?

p (in italics) followed by a less that or equal to sign and a value

ratio level of measurement

highest level of measurement, a true zero point ex. height, weight, age, length

Standard error of the mean indicates

how well the sample mean is likely to represent the population mean.

What are examples of bivariate statistics?

- Chi Square - Correlation - ANOVA - cross tabulations

Pearson's Product Moment Correlation

- Has a sign indicating direction of relationship - Number indicates strength of relationship - Meaningful value when squared

What are examples of univariate statistics?

- Measures of central tendency - Dispersion

Bell-Shaped Curve

- Normal distribution of scores - Cluster around the mean

The different measures of dispersion (3)

- Range - Variance - Standard deviation

3 Levels of Dispersion measure

- Range - the difference between the highest and lowest scores in a distribution of scores - Variance - provides a mathematical index of the degree to which scores deviate from, or are at variance with, the mean. - Standard Deviation - overcomes the problem of variance not being calibrated in the same units as the original data by taking the square root of the variance.

Univariate Variable

- Single variable - Simplest form of data tabulation - Involves the presence of frequency and distribution

Quantitative Analysis

- Starts with little background info - Objective - Deductive and logical - Provides generalizations - Sample size is essential - Goal is to classify and count - Uses measuring instruments

Chi-Square

- Values identified by "x2" - Used to measure data at a nominal level - Used to test distribution frequency to single-variable or to compare 2 or more groups -Chi-square is a nonparametric statistic. -Chi-square is best thought of as a discrepancy statistic (AKA, "goodness of fit").

What are some data tabulation issues?

- hand tabulation is inefficient - human error while recoding - lose sight of micro-level trends - average of data does not show the entire picture - collapsing data lessens precision of analysis

A variable that goes down the side of a cross tabulation table and whose values are in the rows should be the

Dependent Variable

Dispersion measures

Describe the way in which the scores are spread out about a central point

True or False? A cross-tabulation is used when one nominal-level variable and one interval-level variable need to be analyzed simultaneously to see if there's a relationship between them

False

True or False? If you wanted to test more than two mean scores you'd have to use a t-test instead of ANOVA

False

True or False? It is generally assumed that 100% of the scores in a distribution of numbers will fall within plus or minus two standard deviations from the mean, especially if the distribution is believed to be normal

False

True or False? Measures of central tendency and dispersion are examples of bivariate statistics?

False

True or False? When testing for Mr. Pearson's r for statistical significance, the null hypothesis is almost always that the correlation between the two variables in the population is greater than .05

False

What is the most important feature of a normal curve?

Fixed areas below the normal curve represent the frequency of the scores of values of a variable that fall in those areas. Allows us to know how variables vary without measurement

Are summary descriptive statistics a way to reduce data?

Yes. - Measures of Central Tendency - Mean, Median, Mode

parameter

a characteristic of a population and is generally unknown.

statistic

a characteristic of a sample (e.g., average weekly hours spent online by OU Freshmen).

True or False? The Median and Mean can be used to analyze all four levels of measurement

false