basic concepts of inferential statistics
DESCRIPTION
Know what inferential statistics is and its process. Also discover about various sampling techniques.TRANSCRIPT
Basic Concepts of Inferential Statistics
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WHAT IS INFERENTIAL STATISTICS?
Inferential statistics is a technique used to draw conclusions about a population by testing the data taken from the sample of that population.
It is the process of how generalization from sample to population can be made. It is assumed that the characteristics of a sample is similar to the population’s characteristics.
It includes testing hypothesis and deriving estimates.
It focuses on making statements about the population.
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THE PROCESS OF INFERENTIAL ANALYSIS
Raw
Data
• It comprises of all the data collected from the sample.
• Depending on the sample size, this data can be large or small set of measurements.
Sampl
e Statistics
• It summarizes the raw data gathered from the sample of population
• These are the descriptive statistics (e.g. measures of central tendency)
Inferential
Statistics
• These statistics then generate conclusions about the population based on the sample statistics.
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SAMPLING METHODS
Random sampling is the best type of sampling method to use with inferential statistics. It is also referred to as probability sampling.
In this method, each participant has an equal probability of being selected in the sample.
In case the population is small enough then everyone can be used as a participant.
Another sampling technique is Snowball sampling which is a non-probability sampling.
Snowball sampling involves selecting participants on the basis of information provided by previously studied cases. This technique is not applied for inferential statistics.
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IMPORTANT DEFINITIONS
Probability is the mathematical possibility that a certain event will take place. They can range from 0 to 1.00
Parameters describe the characteristics of a sample of population. (Variables such as age, gender, income, etc.).
Statistics describe the characteristics of a sample on the same types of variables.
Sampling Distribution is used to make inferences based on the assumption of random sampling.
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SAMPLING ERROR CONCEPTS
Sampling Error: Inferential statistics takes sampling error (random error) into account. It is the degree to which a sample differs on a key variable from the population.
Confidence Level: The number of times out of 100 that the true value will fall within the confidence interval.
Confidence Interval:A calculated range for the true value, based on the relative sizes of the sample and the population.
Sampling error describes the difference between sample statistics and population parameters.
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SAMPLING DISTRIBUTION CONCEPTS
The variables of a sample taken from
the population
should be the same for the population
also.
Due to sampling error, the
sample mean can be varied.
The amount of this
variation in the sample
mean is referred to as
standard error.
Standard error
decreases as the sample
size increases.
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TYPES OF HYPOTHESES
Alternative hypothesis: It specifies expected relationship between two or more variables. It may be symbolized by H1 or Ha.
Null hypothesis: It is the statement that says there is no real relationship between the variables described in the alternative hypothesis.
In inferential statistics, the hypothesis that is actually tested is the null hypothesis. Therefore, it is essential to prove that the null hypothesis is not valid and alternative hypothesis is true and should be accepted.
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HYPOTHESIS TESTING PROCESS
State the research
hypothesis
State the null hypothesis
Choose a level of statistical significance
Select and compute the test statistic
Make a decision regarding whether to
accept or reject the null
hypothesis.
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