Market Research Flashcards
3 ways in which Data is prepared & Define
- Data Entry: Convert data to electronic form
- Data coding: Group and assign numeric codes to responses
- Data Cleaning: Check for errors & inconsistencies
What is an example of data coding?
I.E. female=1 male =2
What are the types of errors & inconsistencies that can be found during data cleaning?
Skipping patters: Answers when they shouldn’t or doesn’t when they should
Incompleteness
Impossible values: IE age = 999
“Straight lining”: occurs when survey respondents give identical (or nearly identical) answers to items in a battery of questions using the same response scale
What is descriptive statistics?
Summarizes data
Measures of Central Tendency: using Mean, Median, Mode as well as
Measures of dispersion: Standard Deviation, Variance and Range
What type of data can be measured using mean, median and mode?
Mean: Interval/Ratio
Median: all except nominal
Mode: any
How is the mean & SD calculated?
Mean: sum x/number of x
SD: sqrt[sum( X(i)-mean)^2/ (n)]
How is variance calculated?
Var = sum (X(i)-mean)^2/(n)
How is the sample SD and the population SD differ?
The samples SD uses n-1, whereas the population SD is n
What is a one way frequency table?
Table that shows number of respondents choosing each answer yo a survey question
Application Rule for Frequency Tables
Always applicable, but not always effective if the variable contains too many values
What measurement scales is used for Mean, Median, Mode?
Nominal: Mode
Ordinal: Mode & Median
Interval/Ratio: Mode, Median, Mean
Covariance
How much two random variables change together
Pearson Correlation
A scaled version of covariance:
when p=0 no relationship,
|p|<0.3 weak
|p|> 0.49 strong
2 caveats on correlation
- When p=0 there is no Linear Correlation, which means there may be non linear relationships
- Measures how closely data is scattered around a linear line & has nothing to do with the slope
How do you interpret the crosstabulation?
Lecture 12 Slide 2 - photo
What questions does the chi-square analysis answer?
Are the percentages found on a cross tab table actually different or did they happen by chance, or is it an overall population pattern?
What is a hypothesis?
Is an assumption that a researcher makes about some characteristics of the population
Null hypothesis?
The status quo, no effect, no relationship, no difference.
Alternative hypothesis
There is an effect, there is a difference, relationship
What are the hypothesis framework?
- Hypothesize something about the population H0
- Measure the chance of observing the sample if H0 is true
- If the chance is high accept H0, if it’s low reject the H0 and conclude H1
Test Statistic
Is a standardized value that is calculated from the sample data during a hypothesis test conditional on the null hypothesis.
IE z-score, t-test, F-statistic, x^2
P-Value
It measures how likely we can observe the sample data if the null hypothesis is right.
If p is small the null must go
Significance Level
Compare the p value to our significance level. Usually 0.05
We reject the null when ____ is less than the ______
P- value
Sig level
5 steps in hypothesis testing
- State the hypothesis
- Choose the appropriate test based on the problem
- Develop a decision rule
- Calculate the value of the test statistic/p-value
Decision Rule
A standard to reject or fail to reject the null hypothesis.
P-value, Significant Value
When you look at SPSS where is the test statistic? Where is the P-value?
Pearson Chi-Square & Value = Test statistic
Pearson Chi-Square & Asymptotic Significance = P-Value
How do you state the conclusion?
With 95% confidence we can/ cannot reject the null hypothesis that there is not relationship between X and Y
Explain the types of errors?
Type 1: False Positive
Type 2: False Negative
Type I or II?
The person is innocent but you conclude that the person is guilty
The person is guilty but you conclude that the person is innocent
Type 2: False Negative
Type 1: False Positive
When do you use the Chi-Square test?
Chi-square Test when you want to examine the relationship of two nominal/ordinal
variables
• Compare the proportions (nominal/ordinal) of different groups
What is this problem type?
Do people’s perception of PCs have changed after seeing the ads?
Problem Type: Compare the mean of an (interval/ratio) variable to a number
One-Sample T-Test
Do purchase intents of a PC vary between people who have and have not seen the ads?
Problem Type: Compare the mean of an (interval/ratio) variable of different groups (2 groups)
Independent Sample T-Test
Do purchase intents of a PC vary among people who have PC only, who have Mac only, and who have both?
Problem Type: Compare the mean of an (interval/ratio) variable of different groups (more than 2 groups)
One-Way Anova
Do people rate the importance of quality and that of reliability differently?
Problem Type: Compare the means of two (interval/ratio) variables
Paired Sample